ANKARA (Reuters) - Turkish police detained 15 suspects in an operation involving raids across the southeastern province of Adana targeting the Kurdistan Workers Party (PKK) militant group, the state-run Anadolu Agency said on Sunday.

The raids come as fighting between security forces and PKK militants in the largely Kurdish southeast has escalated to new heights since the collapse of a 2-1/2-year ceasefire between the state and the militant group in July of last year.

On Friday, a car bomb in the mainly Kurdish city of Diyarbakir killed 11 people and wounded at least 100, hours after Turkish authorities detained the leaders and lawmaker of the main pro-Kurdish opposition Peoples' Democratic Party (HDP), whom the government accuses of links to the PKK.

Officials blamed the autonomy-seeking PKK, citing radio intercepts, although Islamic State also claimed responsibility for the attack, according to the group's Amaq news agency. Kurdish militants, Islamic State radicals and far leftists have all staged attacks on civilians in Turkey in recent years.

Anadolu said the anti-terror police raids, backed by helicopter, were carried out simultaneously at various spots across the city.

In security operations over the past week, 28 PKK militants were "neutralized", the Interior Ministry said on Monday.

More than 40,000 people have been killed in the conflict since the PKK took up arms in 1984. It is considered a terrorist group by Turkey, the United States and the European Union.

(Writing by Tuvan Gumrukcu; Editing by Nick Tattersall)