A second train which travelled to the scene to provide assistance was fired on by militants armed with rifles, an official said. It was not clear if there were any casualties in this attack.

The state-run Anatolian news agency said a postal train was targeted in the first attack. The five dead and three of those injured were soldiers travelling on the train in Bingol province between the eastern towns of Elazig and Tatvan when the blast occurred around 10:15 a.m. (0715 GMT).

One official said rebels from the separatist Kurdistan Workers Party (PKK) were believed to have laid the C-4 plastic explosives on the track and triggered them by remote control. A military operation was launched to capture those responsible.

The blast toppled carriages, and work had begun to rescue people trapped inside, an official said. Around 100 people were on board the train at the time. The injured were being transported to hospital by helicopter.

More than 30,000 people have been killed in the PKK's armed campaign for self-rule in southeast Turkey since they took up arms in 1984.

The clashes tailed off after PKK leader Abdullah Ocalan was captured and jailed in 1999, but there has been a resurgence of violence since the group called off a unilateral cease-fire last year.

On Friday, police shot dead a suspected suicide bomber at the Justice Ministry after he apparently tried to set off an explosive device near Prime Minister Tayyip Erdogan's office.

Police grabbed him after he apparently set off a detonator but failed to explode his main device. He escaped into the street where police shot him.

Police gave the bomber's name as Eyup Beyaz and said he was known to be a member of Turkey's largest far-left faction, the Revolutionary People's Liberation Party-Front (DHKP-C).

Turkey has a long history of bombings mounted by a wide range of groups, from leftists to Islamists and the PKK, but suicide attacks are rare.