* Warns 'reborn' Ukrainian people will be tough on new leaders
* Wants to slash numbers of bureaucrats, red-tape
* Oligarch Poroshenko to face Tymoshenko in May 25 election
By Paul Ingrassia and Richard Balmforth
KIEV, April 6 (Reuters) - Ridding Ukraine of corruption is key for any new leadership, says presidential candidate Petro Poroshenko, who warns that failure will anger a "reborn" people with high expectations for real change after months of turmoil.
Poroshenko, a confectionery billionaire who is one of two leading candidates in a May 25 election, said Ukrainians had earned the right to a path to membership in the EU after the revolt that threw off president Viktor Yanukovich.
But in an interview with Reuters he also said he would not seek to join the NATO Western military alliance, a move he said would risk dividing the country while Russian troops are massed on its frontier.
After the ousting of Yanukovich, the killings of more than 100 protesters and Russia's seizure of Crimea, people will demand a radical shift by future leaders away from the sleaze and malpractice of the past, said Poroshenko, 48.
"A new country was born and a new people was born," Poroshenko, a strong-built man with a shock of greying hair, told Reuters in Kiev, striking the table for emphasis.
"If the president, the government and the parliament do not demonstrate a different style and show that we live in different conditions, people after half a year, nine months, will say 'OK' and withdraw their support," he said. "They (the future leaders) should know why 104 people gave their lives."
The May 25 election will be a first step by the interim leadership to get Ukraine back on its feet after four months of turbulence and confrontation with Russia that has traumatised the country and highlighted old east-west divisions.
Poroshenko, known as the "Chocolate King" for the chain of confectionery shops that earned his fortune, is an experienced politician who held a variety of portfolios, including economy minister and foreign minister, under both pro-Western and Moscow-backed administrations.
He will be up against flamboyant former Prime Minister Yulia Tymoshenko, who has a strong core following but is a divisive figure whose many foes could rally around Poroshenko.
Poroshenko's chances improved with the endorsement of heavyweight boxer Vitaly Klitschko, a leader of the anti-Yanukovich movement who bowed out of the presidential race in his favour. But his wealth could help Tymoshenko campaign against him as an "oligarch".
Seated in the Kiev offices of his foundation in front of the national flag and the blue and gold-starred European Union banner, Poroshenko spoke of the need to modernise Ukraine to take advantage of a "unique situation" in which there was real support for integration with the European mainstream.
A vital part of this modernisation, he said, was getting rid of systemic corruption which blights all spheres of life including the economy, and deters foreign investment.
After a values-driven people's revolution against sleaze and state theft under Yanukovich, people will be tough on the new elected leaders and will have little tolerance if they slip back into old corrupt habits, he said.
Corruption mainly takes the form of bribe-taking to ensure public services and penetrates all levels of life including the police, the health service and the education system. Running any business in Ukraine requires paying to ensure operating licences are delivered by local and national authorities.
"ZERO-TOLERANCE" FOR CORRUPTION
"There must be zero-tolerance for corruption. We should seriously cut the number of bureaucrats in the country and cut the (paperwork) in the country because the system simply does not need that," he said.
The practice of bribe-taking deters much-needed foreign investment. "Just imagine. You can fly to Ukraine from any European capital in just two hours. You don't need a visa. You can come to a very safe and very nice country with very experienced labour ... and the only obstacle to that is corruption. That is why it is a top priority."
Poroshenko, whose fortune is estimated by Forbes to be worth $1.3 billion, quickly spotted the changing mood as protests began late last year against Yanukovich's retreat from European integration.
He threw his weight behind the pro-Europe "Euromaidan" movement, appearing with opposition leaders on Independence Square - known as the Maidan - the launchpad of the uprising.
Crucially, he devoted his "5th Channel" TV station to coverage of the protests, turning it into a conduit for interviews and opinions which state-owned channels shunned.
His heavy pro-Europe stance brought him early attention from Russia. Last year Russia's consumer watchdog banned imports of sweets from his Roshen chain of outlets and Russian authorities have closed down a Roshen factory in the town of Lipetsk pending an investigation into alleged malpractice there.
With an agreement on political association already signed with the European Union, it will be now down to the newly-elected president to agree a free trade pact with the EU bloc.
This, he hoped, would lead to "ambitious" reforms in Ukraine that would sustain a bid for membership of the EU.
"In the very near future we would ask our European partners ... for a membership perspective because the Ukrainian people have passed a very difficult and very important exam," he said.
After Crimea's annexation by Russia, a move which the West was powerless to help Ukraine resist, Poroshenko saw a need for a new security architecture for Europe that would afford protection for non-bloc countries like Ukraine.
"The concentration of 30,000 Russian forces on Ukraine's border and the destabilisation of the situation in nine (Ukrainian) regions of the east and south, have produced the most serious threat from the Russian Federation since the time of the Cold War," he said.
The Ukrainian armed forces needed to be modernised to produce a force that was "modern, with a quick reaction ... with the ability to defend" - an area where Ukraine would look for cooperation with the EU and the United States.
Asked about association with NATO, he pointed to growing support in some parts of Ukraine for closer ties with the U.S.-led military alliance after the Russian military incursion. But he said that swell of support was not great enough to press for NATO membership and said the issue "could split the country".
"If you are asking: what is the top priority? Is it to be in NATO or keep the unity of the country? My answer would be: keep the unity of the country," he said.
Cooperation and dialogue with Russia would be essential in the future, he said. But on Crimea he was adamant.
Ukraine would continue to press by all international and judicial means to "retrieve our territory." "There can be a compromise (with Russia) only after de-occupying Crimea," he said. (Writing by Richard Balmforth; Editing by Peter Graff)