Turkey's state-run news agency says police have launched raids in Ankara and three other cities, detaining some 20 people suspected of illegally eavesdropping on President Recep Tayyip Erdogan and other senior officials.

Anadolu Agency says the suspects, detained early on Tuesday, are linked to Turkey's telecommunications authority and to its scientific and technological research center. They are suspected of wiretapping phones, included encrypted ones used by government officials.

Last year, secretly taped telephone conversations suggesting corruption were leaked on the Internet, including one between Erdogan and his son.

Erdogan has insisted the tapes were fabricated as part of a plot orchestrated by followers of an influential Islamic movement led by US-based cleric Fethullah Gulen.

Dozens of police officers have also been arrested on illegal wiretapping charges.