The explosion ripped through the local headquarters of Erdogan's ruling Justice and Development Party (AKP) in the city of Hakkari at 2:00 pm (1200 GMT), causing wide damage and blowing out the windows of nearby buildings.

A party official, speaking on condition of anonymity, said they suspected the blast was caused by a percussion bomb. There was no statement from the police.

Hakkari, near the border with Iraq and Iran, is at the heart of a 24-year armed drive by the outlawed Kurdistan Workers' Party (PKK) for self-rule in the mainly Kurdish east and southeast that has claimed some 44,000 lives.

The Turkish military has recently stepped up operations against the PKK both inside Turkey and in neighbouring northern Iraq, where Ankara charges some 2,000 rebels take refuge.

The blast coincided with clashes between Kurdish demonstrators and police as Erdogan visited the eastern city of Van.

Fighting erupted when the demonstrators, numbering a few hundred, refused orders to disperse, pelting officers with stones and Molotov cocktails and setting fire to seven vehicles, a local security source said.

Police responded with tear gas and warning shots into the air.

A police officer and a civilian were injured in the scuffles, while several demonstrators -- mostly supporters of the country's main Kurdish party, the Democratic Society Party (DTP) -- were detained.

Speaking to a large crowd just 150 metres (164 yards) from where the scuffles took place, Erdogan brushed aside the protests and pledged steps to increase the prosperity of the Kurdish community.

"I visit and will visit every centimetre of this country.... We bring love, peace, fraternity and welfare to all the places that we visit," Erdogan told the cheering crowd in televised remarks at a ceremony to inaugurate a government housing project.

The Turkish prime minister will leave the city later Saturday after talks with local officials, party members and non-governmental organizations.

In a separate protest, also organized by the DTP, some 4,000 Kurds launched a two-day sit-in protest in Diyarbakir, the main city in Turkey's mainly Kurdish southeast, to denounce government policies against Kurds and the alleged mistreatment of PKK leader Abdullah Ocalan.

Police beefed up security measures around the square where the protest was held, but the situation was calm, an AFP correspondent said.

There were violent Kurdish protests across the country last month after Ocalan's lawyers claimed he had been assaulted by a guard and threatened with death in his cell.

Ocalan is the sole inmate on the prison island of Imrali, northwestern Turkey.

The Turkish government has denied the allegations.

Arrested in Kenya in 1999, Ocalan, 60, was condemned to death, but the sentence was commuted to life imprisonment in 2002 after Turkey abolished capital punishment.