By Ece Toksabay
SILIVRI, Turkey, March 18 (Reuters) - Turkish prosecutors summed up their case on Monday against those accused of plotting to overthrow Prime Minister Tayyip Erdogan's government, seeking life terms for an ex-military chief and other retired generals.
Retired armed forces commander Ilker Basbug was among 275 defendants whom prosecutors accused of attempting to stage a coup as part of the "Ergenekon terrorist group", an alleged underground network of secular arch-nationalists.
Erdogan's ruling AKP party has Islamist roots.
The four-year-old trial has drawn accusations of political influence over the judiciary. The defendants include academics, politicians and journalists, as well as former army officers.
"It has become clear that the Ergenekon terrorist group exists," state prosecutor Mehmet Ali Pekguzel told the court within a huge prison complex at Silivri, west of Istanbul.
The defendants will now have the opportunity to make their final defences, a process which could take another couple of months, before a verdict is announced.
Ergenekon is accused of being at the heart of political violence, extra-judicial killings and bomb attacks which scarred Turkey in recent decades - an embodiment of anti-democratic forces which Erdogan says he has fought to stamp out.
Critics see the case as a ploy to stifle opposition, part of a grand plan by the leader to tame the secularist establishment, including an army that intervened to topple governments four times in the second half of the 20th century.
Investigation of the alleged conspiracy, which surfaced in 2007 when police discovered a cache of weapons in Istanbul, was initially welcomed by a public eager to see an end to the "Deep State" - a shadowy network of militant secularists long believed to have been pulling the strings of power.
But dissenting voices have grown over the last five years, with the European Commission expressing concern about the handling of Ergenekon and other conspiracy trials. (Writing by Daren Butler; Editing by Alistair Lyon)