* Bashir's military confidant replaces veteran Islamist
* Bashir faces international arrest warrant, internal unrest
* President says will not run in 2015 election
By Khalid Abdel Aziz and Maggie Fick
KHARTOUM/CAIRO, Dec 10 (Reuters) - Sudanese President Omar Hassan al-Bashir's appointment of an old military ally as his deputy may shield one of Africa's longest-serving rulers from risks at home and abroad.
In a government shake-up, Bashir named Lieutenant General Bakri Hassan Saleh - a confidant who helped him stage his 1989 coup and crush many rebellions - as first vice president, replacing veteran politician Ali Osman Taha.
By positioning Saleh one step away from his own job, Bashir may be crafting a strategy to avoid being handed over to the International Criminal Court on charges of genocide if he keeps his promise to step down in 2015.
The reshuffle announced on Sunday by Bashir underscores the diminishing role of Islamists such as Taha as the president turns to more trusted allies in the military, an organisation important to his survival in a country with a history of coups.
"(Saleh) is a political clone of Bashir, and his appointment consolidates the military at the heart of politics," Alex de Waal, a Sudan expert and head of the World Peace Foundation at Tufts University in the United States.
"This is Bashir's protection plan and signals that (he) may be ready to step aside if (Saleh) is his successor."
While Sudan has avoided sustained political unrest seen in other Arab states over the last three years, Bashir and his ruling cadre have been on more fragile ground since the oil-rich south of Sudan broke away in 2011 after voting for independence, depriving the north of badly-needed revenues.
Facing rivals within his own ruling National Congress Party, Bashir's government has struggled to cope with a tanking economy and rising inflation since the South's secession.
Aside from still-simmering revolts near the border with South Sudan and an unresolved conflict in the western Darfur region, Bashir has recently faced troubles close to home.
A government decision to cut fuel subsidies in September to ease the financial crunch served as a reminder that he must tread cautiously in a region where protests have toppled several autocratic Arab leaders since 2011.
The move doubled pump prices overnight and triggered violent demonstrations in which dozens of people were killed. Thousands of Sudanese demanded that Bashir step down in the biggest opposition rally for years.
The crackdown by security forces also drew criticism from within his own party.
Overseas, Bashir has arrest warrants hanging over him by the ICC on charges of orchestrating war crimes and genocide in Darfur. Sudan dismisses the ICC charges, saying reports of mass killings in Darfur have been exaggerated, and refuses to recognise the court, which it says is part of a Western plot.
Since he came to power as an obscure army brigadier in a bloodless coup, Bashir has skillfully played divide-and-rule politics with rival factions among the security services, the military, Islamists and armed tribes.
The strategy has worked. In his 24 years in power, Bashir has weathered multiple armed revolts, U.S. trade sanctions, the loss of vital oil to South Sudan and, more recently, a coup attempt by disgruntled officers and Islamists.
Given the array of security challenges and threats to his iron rule, Bashir's choice to install Saleh may prove to be a masterstroke.
He is regarded as a part of a cadre of officers whose interests are served by backing the 69-year old Bashir to avoid international prosecution themselves.
Although Saleh, 64, does not face charges at The Hague, Human Rights Watch has said he should be investigated for his role in Darfur crimes. Saleh served as defence minister in the early stages of the Darfur war that the United Nations says has killed more than 300,000 people.
"The reshuffle in a way is quite a safe strategy to ensure that Bashir is not made vulnerable," said Cedric Barnes of the International Crisis Group, citing the risk of the ICC.
Taha, who was removed in the government shake-up, would have been the succession candidate preferred by many Western diplomats, who hoped his more moderate views might open a new chapter in relations.
Taha, 68, was the most significant remaining Islamist in Bashir's government and was seen as a potential challenger for the presidency in an election due in 2015. He remains in the position of vice chairman in Bashir's party.
Wary of unrest spreading around the Arab world, Bashir said in 2011 that he would not contest the election. He has since been less clear-cut, saying the decision would be made by his National Congress Party.
Bashir is not taking chances either way.
Saleh has been in Bashir's inner circle since the two trained and later fought together as paratroopers before deposing President Sadiq al-Mahdi, leader of Sudan's last elected civilian government.
Saleh has been described as "an efficient and sinister defender of the revolution" by historians Millard Burr and Robert Oakley Collins - using the officers' name for their coup.
Shortly after the takeover, he was assigned to restructure the National Security bureau in the interior ministry.
Under his supervision, a security apparatus that became notorious for human rights abuses was formed.
Saleh was promoted to first vice president from the position of minister for presidential affairs, which he has held since 2005. The majority of the new appointments have military or state security backgrounds and are close to Bashir.
Defence Minister Abdel-Rahim Mohamed Hussein held on to his post. Like Bashir, he faces Darfur-related charges at the ICC.
"Decision-making is now totally in the hands of Bashir, with two officers at his side," said a Sudan expert based in the region who spoke on condition of anonymity.
The cabinet reshuffle was a major blow to Sudan's opposition, with some describing it as a new military coup.
"Now the military and security institutions are singularly leading the country," said Kamel Amr, spokesman for a coalition of the country's most prominent opposition parties.
"We in the opposition see that the very narrow margin of space for freedom in the past will disappear because of the new arrivals from the military."
(Writing by Maggie Fick; Editing by Tom Perry and Michael Georgy/Mark Heinrich)
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