ANKARA (Reuters) - Turkish authorities detained 81 people, most of them foreigners, on Thursday on suspicion of planning to travel illegally to join Islamic State militants in Iraq and Syria, the privately-owned Dogan news agency said.

It said 21 of those detained were suspected of being senior figures in the Islamic State network, while 60 were foreign nationals. It said the operation was centered in Istanbul but involved raids at 31 locations in six Turkish provinces.

Turkey launched a military incursion into Syria in August in support of Syrian rebels to try to push Islamic State away from its border area, and has also frequently carried out raids on suspected jihadist safe-houses in Istanbul and other cities.

Reuters was not immediately able to confirm the report on the latest detentions.

(Writing by Tuvan Gumrukcu; Editing by Nick Tattersall)