* Erdogan has curbed influence of once-powerful military
* Comments seen as distancing from trials after criticism
* Comes after one of most violent years in three decades
By Jonathon Burch
ANKARA, Jan 26 (Reuters) - Turkish Prime Minister Tayyip Erdogan has criticised the lengthy pre-trial detention of hundreds of military officers, suggesting it was sapping army morale just as Ankara vows to keep up pressure on Kurdish militants.
During his 10 years in power, Erdogan, whose party has moderate Islamist roots, has brought to heel the once all-powerful armed forces, which see themselves as guardians of secularism and regularly intervened in politics and carried out coups in previous decades.
Hundreds of serving and retired officers, including 20 percent of military generals, have been jailed pending trial since 2005 on conspiracy charges and plotting to overthrow the government.
But as initial public support for the investigations dwindles, with critics and even sympathisers saying cases have spiralled out of control, Erdogan has distanced himself from the trials.
"There are now close to 400 retired and serving officers inside. The most serious are accused of forming organisations or belonging to one. If the provisions for these are certain, then finish the job," Erdogan said late on Friday.
"But if there isn't certainty, then the hundreds of officers should be treated accordingly. This disrupts the entire morale of the Turkish armed forces. How can these people then fight terror?" he said in an interview with Turkish television.
While Erdogan has received praise for bringing the military under civilian control, the years defendants are spending in prison without conviction has raised fears the trials are a political witch hunt aimed at silencing opposition.
The first large-scale convictions came last September after a 21-month trial when more than 300 officers were handed prison sentences for plotting to topple Erdogan's government almost a decade ago. Hundreds more are still in jail awaiting trial.
Around 100 journalists are also in prison, as well as thousands of activists, lawyers, politicians and others. Most are accused of plotting against the government or supporting outlawed Kurdish militants.
Parliament voted to abolish the special courts used in coup conspiracy cases last July after Erdogan criticised prosecutors for acting as if they were "a different power within the state".
But the end of the special courts, established by Erdogan's government in 2005, will not affect existing prosecutions of the hundreds of military officers already in jail.
Erdogan's latest comments also come after one of the most violent summers in three decades, with security forces locked in almost daily battles with militants from the Kurdistan Workers Party (PKK) and at a time of heightened tension with Syria.
Turkey has been one of Syrian President Bashar al-Assad's fiercest critics and has seen violence from the war in its southern neighbour spill into its own territory. While Ankara does not want to get sucked further into the conflict, it has threatened cross-border military action if needed.
Turkey's conscript army is the second largest in NATO.
The PKK, designated a terrorist group by Ankara, the United States and the European Union, took up arms in 1984 and more than 40,000 people, mostly Kurds, have been killed since then.
The state-run Anatolian news agency reported on Saturday the military killed more than 1,500 "terrorists" inside and outside Turkey last year, citing the country's general staff. Turkish warplanes regularly launch air strikes on PKK targets in northern Iraq, where the guerrillas have bases.
Reuters could not independently verify the militant death tolls and Turkey's military rarely talks to the media.
Security forces, including army and police, have taken heavy casualties over the past year with PKK militants stepping up attacks on convoys and outposts.
Hopes of an end to the conflict grew, however, after the government acknowledged state intelligence officials were talking to jailed PKK leader Abdullah Ocalan.
While backing moves toward peace, Erdogan has vowed military operations will continue until the PKK disarms, a stance Kurdish politicians say undermines efforts to build trust. (Writing by Jonathon Burch; Editing by Jason Webb)