* Ukraine holds presidential election on Sunday
* Kiev's main square still barricaded, 'defended'
* Maidan leaders say new president must meet their demands
By Gareth Jones
KIEV, May 23 (Reuters) - As Ukrainians prepare for Sunday's presidential election, the message from Kiev's main square is clear - the new leader will be closely watched and the people could rise up again if they feel cheated.
Three months after Moscow-backed president Viktor Yanukovich fled the capital in the face of a street uprising, Independence Square, or the "Maidan", still looks like a war zone, bedecked with barbed wire and barricades, covered with tents and patrolled by khaki-clad "defenders" in no hurry to pack up.
"I have been here since December. We will stay here until after the presidential election but the new president and authorities must fulfil our demands for genuine democracy and an end to corruption," said Ivan Stratyenko, 40, one of the "sotniki" or commanders of the Maidan.
"The revolution is not finished. Yanukovich has gone but the system that nourished him and allowed him to plunder the country is still in place," said Stratyenko, a former musician from the city of Lviv in the nationalist-minded west of Ukraine.
"We expect wise but radical actions from our new president."
Opinion polls suggest confectionary magnate Petro Poroshenko will win the election, either in Sunday's first round or - if he fails to muster more than 50 percent of the vote - in a second round set for June 15.
Poroshenko, a former government minister who was once allied to Yanukovich but backed the Maidan protests, is viewed as a pragmatic, experienced operator who will maintain Ukraine's tilt to the West while trying to mend shattered ties with Russia.
Another Maidan commander, Andrei Veremiyenko, made clear the new president would face careful scrutiny, especially after an earlier street uprising, 2004's Orange Revolution, brought in a government many activists consider a discredited failure.
"If they try to go back to the old corrupt system, there will be a third Maidan and it will be more savage than before, much more savage," said the 40-year-old former sports teacher.
"Our demands must be met - namely a decentralisation of power and the creation of a system that truly fights corruption. That is not yet happening," he said. "Bureaucrats are still rigging auctions and taking bribes, those involved in the killing of people on the Maidan have still not been punished."
His remarks were tinged by anger and grief over the deaths of more than 100 people in the uprising, many shot by police snipers while defending the barricades during three days in February.
Amid the camp clutter, the posters, placards and Ukrainian and European flags, photographs of the "Maidan martyrs" - old and young, men and women - greet visitors as they pick their way past the tents where some 1,000 people are said still to live.
But on a sunny May afternoon, the Maidan mood is relaxed. Men in combat gear sit around, gossiping or playing cards. Some, locals say, have no other home to go to or simply prefer the cameraderie of camp life and the belief they are serving a higher cause over the humdrum routine of a normal job.
A woman plays a piano standing near the tents. A young woman wearing a Minnie Mouse costume strolls past an old man dressed in a Cossack uniform who looks somewhat the worse for drink.
Kiev's - and the world's - attention is now firmly focused not on the Maidan but on eastern Ukraine, where troops are clashing daily with the separatists who have declared "people's republics" and say they want to join Russia.
The separatists depict their uprising against Kiev's rule as a mirror image of the Maidan protests that toppled Yanukovich, who came from the eastern region of Donetsk, and replaced him with what many in the east see as a "fascist junta".
Some former Maidan fighters have since signed up to join a newly formed National Guard that is helping to recover territory seized by the pro-Russian separatists in eastern Ukraine. Kiev and the West accuse Moscow of backing the separatists. Russia denies arming them but says their aims are legitimate.
"The troubles in the east have diverted our attention. Instead of fighting Ukraine's internal problems like corruption we are having to deal with the Russian threat, with the separatists in the east," said Veremiyenko.
Kiev's Western-backed interim government hopes Sunday's election will restore normality and stability after months of turmoil that also saw Russia's annexation of Ukraine's Crimea peninsula.
But on the Maidan, views about Ukraine's probable next president are not very positive.
"We are now about to elect another oligarch. We got rid of one gang only to see it replaced by another. I am very disappointed," said Nikolai, 57, a retired soldier. "I am sure that in six months or so, people will again appear on the Maidan with placards shouting 'Ukraine without Poroshenko'," he said.
Nikolai, who declined to give his second name, added that he would vote on Sunday for Yulia Tymoshenko, a feisty but divisive former prime minister and Orange Revolution leader who opinion polls show trailing far behind Poroshenko in second place.
Stratyenko, the musician-turned-commander, agreed that Poroshenko was part of the old system, though "not a bad man".
Irrespective of who wins this election, he added, Ukraine can never return to how things were before Yanukovich's fall.
"The Maidan shows that people are starting to wake up, they want to take on responsibility. We don't want a state dominated by our leaders, that was the Soviet Union. We are the masters now, we are the owners of this country," he said. (Reporting by Gareth Jones; Editing by Peter Graff)