July 9 (Reuters) - Turkish authorities say they hope to file an indictment by the end of the week against men accused of belonging to a group, "Ergenekon", plotting attacks aimed at the overthrow of the AK Party government.

Here are some details of coups over the last 50 years.

1960:

-- On May 3, 1960, the commander of land forces, General Cemal Gursel, demanded political reforms and resigned when his demands were refused.

-- On May 2, an almost bloodless military coup was carried out, led by officers and cadets from the Istanbul and Ankara war colleges.

-- The leaders established a 38-member National Unity Committee with Gursel as chairman. Of 601 people tried, 464 were found guilty. Three former ministers, including Prime Minister Adnan Menderes, were executed and 12 others, including President Celal Bayar, had death sentences commuted to life imprisonment.

1971 - The 'Coup by Memorandum':

-- The Military delivered a warning to the government to restore order after months of strikes and street fighting between leftists and nationalists. Some months later, Prime Minister Suleyman Demirel stepped down and a coalition of conservative politicians and technocrats set to restore order under the supervision of the military. Martial law was established in several provinces and not completely lifted until September 1973.

1980:

-- On Sept. 12, 1980, the senior command of the army led by General Kenan Evren, carried out a bloodless coup. The action followed a resurgence of streetfighting between leftists and nationalists. Leading politicians were arrested, and parliament, political parties, and trade unions were dissolved. A five-member National Security Council took control, suspending the constitution and implementing a provisional constitution that gave almost unlimited power to military commanders.

1997 - The 'Post-Modern Coup':

-- On June 18, 1997 Prime Minister Necmettin Erbakan, denounced by opponents as a danger to the country's secular order, stepped down under pressure from the military, business, the judiciary and fellow politicians. The generals saw themselves compelled to act to defend the secular state founded by Mustafa Kemal Ataturk.

2008:

-- Twenty-one prominent Turks, including two former military commanders, businessmen and journalists, have been detained in a 13-month-old police investigation into allegations of a plot to unseat the government.

-- Government opponents have questioned the coup allegations, pointing to the fact that no indictment has been released despite a 13-month long nationwide investigation.

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