* Erdogan says he now facing a new "dirty plot' to unseat him
* Hundreds convicted in Ergenekon, Sledgehammer conspiracies
* Analyst says Erdogan seeking to discredit Gulen movement (Adds analyst, bar association, jailed general, Gulen letter)
By Daren Butler
ISTANBUL, Jan 6 (Reuters) - Turkish Prime Minister Tayyip Erdogan has mooted the retrial of hundreds of army officers convicted of planning his overthrow, in an apparent attempt to discredit rivals he accuses of contriving a corruption crisis to drive him from office.
Erdogan's Islamist-rooted AK Party is widely held to have relied heavily on U.S.-based Islamic cleric Fethullah Gulen's influence in the police and judiciary in breaking the power of an army that carried out three coups between 1960 and 1980 and forced an Islamist-led government from power in 1997.
Now Erdogan followers, facing what they term a dirty plot by Gulen's secretive Hizmet (Service) movement to tar the cabinet with corruption accusations, suggest some officers jailed in the "Sledgehammer" trials that helped rein in army power may have suffered injustice by police or judiciary.
The clash between the erstwhile allies, now apparently extending to the highly sensitive issue of the army, has dealt a blow to Erdogan. His decade in power has seen strong economic growth and stability questioned only by widespread summer protests over wht critics regard as his authoritarian style.
"There is not a problem for us about retrials as long as the legal basis is established," Erdogan told reporters late on Sunday before leaving on an official visit to Asia. "In terms of regulations, we are ready to do what we can."
The army, which has in the past hinted at concerns over Hizmet, has filed a criminal complaint, arguing evidence against serving and retired officers had been fabricated.
A review may also cover military, businessmen, journalists and politicians jailed in a separate "Ergenekon" investigation.
The graft scandal exploded on Dec. 17 with the detention of businessmen close to the government and sons of three cabinet ministers since resigned. The government has hit back by dismissing or reassigning hundreds of police officers across the country and blocking a second investigation of large infrastructure projects he has backed.
Erdogan and Hizmet, which exercises influence through a network of contacts built on sponsorship of schools and other social and media organisations, accuse each other of manipulating police and compromising the independence of the judiciary.
Erdogan, still by far the most popular politician, accuses Hizmet of creating a "state within a state" backed by foreign forces hostile to Turkey.
What had been common ground between Erdogan and Gulen - the taming of the army - appears now to have soured into a conflict parallel with the corruption dispute.
Security analyst Gareth Jenkins, who has followed the coup plot trials closely, said the latest move by Erdogan appeared to be aimed at discrediting the Gulen movement.
"If he can publicise the fabrications of evidence, the tampering of evidence and everything else that happened during these trials then he will discredit the Gulen movement directly," Jenkins told Reuters.
"It will also help him to try to undermine the accusations the movement is making against him in terms of corruption. I can see the logic in what he is trying to do," he said.
After meeting top Ergenekon defendants in Silivri jail near Istanbul on Monday, bar association head Feyzioglu proposed formulas for a retrial, including the complete abolition of the special authority courts which heard the two cases.
"If this country's prime minister, interior minister and advisers have said 'there is a parallel state grouping within the judiciary' and 'the TSK (armed forces) have been plotted against', it is impossible for us to ignore this," he said.
"Today a serious legal tragedy is taking place," he said after meeting the most senior Ergenekon defendant, former armed forces chief General Ilker Basbug.
A court on Monday rejected Basbug's latest bid to be released and he railed against his continued detention on what was the second anniversary of his imprisonment in Silivri.
"Two stolen great years. Stolen from my life, the life of my family and those close to me... I don't know how long this theft, this robbery will continue," he said on his official Twitter account.
In an apparent bid to resolve the conflict between the government and Gulen movement, Gulen wrote a letter to "dear friend" President Abdullah Gul on Dec. 22, media reports revealed at the weekend.
"I am ready to do all I can in my talks to lower the tension and recommend restraint to our friends and followers," Gulen wrote, according to a full text of the letter published by the pro-government Yeni Safak daily.
He also expressed sadness at "black propaganda" spread by some media targeting his supporters and purges of civil servants seen as close to the movement.
Gulen's letter was written before a second corruption investigation emerged and acrimony has grown since then, with Yeni Safak columnist Cem Kucuk saying it was too late for what he described as a call for peace and negotiation.
"From this moment forward there can be no peace. The government must do what is necessary regarding this structure which questions its legitimacy and it will do. All elements of the junta will be called to account one by one," he wrote. (Additional reporting by Seda Sezer; Writing by Nick Tattersall; Editing by Ralph Boulton)