ANKARA (REUTERS) - Turkey's parliament on Thursday approved a law boosting the powers of the secret service (MIT), a move seen by Prime Minister Tayyip Erdogan's critics as a bid to tighten his grip on the apparatus of state as he wages a bitter power struggle.

The changes ratified by parliament, which is dominated by Erdogan's AK Party, give the MIT more scope for eavesdropping and foreign operations, as well as greater immunity from prosecution for top agents.

Control of the NATO member's security apparatus is at the heart of a feud between Erdogan and Islamic cleric Fethullah Gulen, a former ally based in the United States whose network of followers wields influence in the police and judiciary.

Erdogan accuses Gulen's network of orchestrating a plot to unseat him, tapping thousands of phones, including his own, over years and using leaked recordings to unleash corruption allegations against his inner circle in the run-up to a series of elections. Gulen denies involvement.