The peace group's 34 members, including eight Kurdistan Workers' Party (PKK) rebels, were taken in for questioning as soon as they walked through the Habur gate on the border between Iraq and Turkey.

Four prosecutors sent to the border area to meet the group were to determine whether those held had committed any crimes and should be taken into custody.

Rallies in support of the group were held in several cities. Some 5,000 people gathered in a central square in Diyarbakir, the biggest city in the mainly Kurdish southeast, answering a call by Turkey's main Kurdish party, the Democratic Society Party.

"Welcome peace ambassadors! Hand in hand for an honourable peace," chanted the protestors, along with slogans in favour of Abdullah Ocalan, the jailed leader of the rebel PKK.

Similer demonstrations took place in Batman and Mardin in the southeast and the eastern cities of Tunceli, Van and Mus, as well as Izmir in the west and the country's biggest city Istanbul, both of which have sizeable Kurdish communities.

A large crowd -- around 2,500 people, according to police -- marched down Istiklal Avenue, the main commercial street in Istanbul's European quarter, behind a banner which read "Open the Way for Peace".

"The ambassador of peace is in Imrali," the protestors shouted, in reference to the prison island where Ocalan has been held since his capture in 1999.

"Bravo PKK, the people are here," they said, flashing the V-sign for victory.

The PKK announced last week that it would send "peace groups" from Iraq and Europe, on a proposal from Ocalan, to help advance Ankara's bid for peace.

Since August, the government has been trying to build public support for an iniatitive to grant Kurds greater rights and try to erode support for the PKK, which has been fighting for self-rule in the southeast since 1984.

The government however rejects dialogue with the rebels and has vowed to pursue military action against them.

More than 45,000 people have been killed since the PKK picked up arms in Turkey's Kurdish-populated southeast and east.