Updated

Syria is allowing Kurdish rebels who are fighting Turkish forces to establish bases in Syrian territory, as ties between the two neighboring countries deteriorate, a Turkish minister said Wednesday.

Interior Minister Idris Naim Sahin said Turkish intelligence indicates that Syria is allowing rebels to establish themselves in areas close to the Turkish border. Some Kurdistan Workers' Party rebels have even taken charge of running small Syrian towns, Sahin claimed, describing the development as an apparent act of revenge against Turkey.

Turkey has reacted to the popular uprising in Syria by urging its leader, Bashar Assad, to step down, by accepting some 23,000 Syrian refugees in Turkey, and by playing host to civilian and military members of the Syrian opposition.

Kurdish rebels have long used bases in northern Iraq to launch attacks in Turkey, but Syria had stopped allowing that.

"Terrorist groupings that were not there a year ago have been spotted," Sahin told private NTV television. "Syria is turning a blind eye to terrorist groupings in areas close to the border to put Turkey in difficulty and perhaps as a way to take revenge on Turkey."

The Kurdistan Workers' Party, which has been fighting for autonomy in southeast Turkey for decades, has been condemned as a terrorist group by Turkey, the European Union and the United States.

Turkish officials have accused Syria of reviving its ties with the Kurdish rebels, and Sahin's statement came a week after three Turkish military officers were killed in fighting with suspected rebels in the mountainous region of Amanos near the Syrian border. It was the first such clash reported there in several years.

Syria is believed to have stopped harboring Kurdish rebels in 1998, when Turkey threatened military action. Ties between the two countries also improved after Turkish Prime Minister Recep Tayyip came to power in 2003, and Damascus was cooperating with Turkey in its fight against the Kurdish rebels until ties soured over Syria's bloody crackdown on civilians.

The Kurdistan Workers' Party rebels took up arms in Turkey in 1984, and tens of thousands of people have died in the conflict .