Interior Minister Besir Atalay said the suspects were detained over Tuesday's blast, which claimed five lives, stressing that "the incident is about to be thoroughly enlightened," Anatolia news agency reported.

It was not clear whether the suspected perpetrators of the attack were among the detainees, rounded up in an operation by anti-terror police and special forces, according to Anatolia.

Kurdish militants claimed responsibility for the blast, the latest episode in surging violence since jailed rebel leader Abdullah Ocalan said last month he was ditching efforts to seek dialogue with Ankara to end to the 26-year Kurdish conflict.

The roadside bomb, detonated by remote control, targeted a bus carrying army personnel to work, killing four soldiers and the teenage daughter of an officer and wounding about a dozen people.

Ocalan's Kurdistan Workers' Party (PKK) had threatened to spread violence to urban areas after it killed 12 soldiers in weekend attacks in remote regions in the mainly Kurdish southeast.

Also Wednesday, Prime Minister Recep Tayyip Erdogan slammed European countries for inadequate support against the PKK, listed as a terrorist group by Ankara and much of the international community, including the EU.

"Despite bloody attacks against civilians and security forces (in Turkey), there are countries which have failed to cut the financial channels of the terrorist organisation, turned a blind eye to its activities and propaganda and failed to extradite criminals," Anatolia quoted him as saying.

Ankara says the PKK obtains much of its finances through drug trafficking, people smuggling, extortion and money laundering in Europe through an extensive support network among Kurdish immigrants.

It has long accused European Union countries of tolerating PKK activities on their soil and failing to close down organisations linked to the rebels.

Copenhagen notably has angered Ankara for refusing to ban a Denmark-based television channel, Roj TV, which Turkey says is a PKK mouthpiece.

The dramatic rise in PKK attacks has triggered nationwide outrage in Turkey and turned up pressure on Erdogan for tougher measures against the group, with many also urging him to shelve plans to expand Kurdish freedoms.

Popular anger simmered at the funeral of the youngest victim of Tuesday's blast, 17-year-old high school student Buse Sariyag, who was travelling on the bus with her father. She was laid to rest in Elmadag, an Ankara suburb.

"The martyrs are immortal, the motherland is indivisible," shouted a crowd of some 5,000 people, waving Turkish flags, as they marched to the cemetery.

Army chief Ilker Basbug and Deputy Prime Minister Cemil Cicek attended the funeral ceremony.

The government has pledged to boost Kurdish freedoms and economic development in the southeast, hoping to discourage separatism and cajole the PKK into laying down arms.

Erdogan said Tuesday he remained committed to the pledges despite the violence.

Keen to boost its EU membership bid, Ankara has already granted the Kurds a series of cultural rights, including the inauguration of a Kurdish-language channel on public television last year.

Ankara however rejects dialogue with the PKK, insisting the rebels should either surrender or face the army.

The PKK took up arms for self-rule in the southeast in 1984, sparking a conflict that has claimed some 45,000 lives.