(Writes through with seven detained, adds interior minister)

DIYARBAKIR, Turkey, Jan 8 (Reuters) - Turkish authorities have detained seven people over last week's bomb attack in the southeast city of Diyarbakir, the state's Anatolian news agency said on Tuesday, as the death toll from the blast rose to six.

"In the shortest period of time our security forces will determine the identity of the perpetrators and their accomplices," the agency quoted Interior Minister Besir Atalay as saying as he announced the latest detentions.

The agency earlier reported one man detained, saying he had received training in Kurdish PKK rebel camps in northern Iraq.

Prosecutors freed four other suspects at the weekend without charge.

A young student died of injuries suffered in the blast, hospital officials said on Tuesday. Four of the other five victims were also students.

The blast had targeted military personnel but occurred near a private school in the city centre. The Kurdistan Workers Party (PKK) said on Monday via a news agency close to the group that members working independently may have been behind the blast, the first semblance of a claim of responsibility since the attack.

In the eastern province of Van, bordering Iran, Turkish security officials on Tuesday confiscated 640 kg (1,411 lb) of ammonium nitrate, an explosive used in bomb making, as well as fuses and detonators, the military General Staff said.

The Turkish military, the second largest in NATO, has been waging an aerial bombing campaign against PKK targets in northern Iraq after the United States began sharing intelligence on the rebels' movements.

Turkish commandos have also staged limited raids into Iraqi territory, though commentators say a full-blown invasion remains unlikely despite the presence of as many as 100,000 troops along the mountainous border with Iraq.

Ankara blames the PKK for the deaths of nearly 40,000 people since 1984 when it took up arms to fight for an ethnic homeland in southeastern Turkey. The United States and European Union, like Turkey, classify the PKK as a terrorist organisation.

The fight against the PKK was expected to dominate talks on Tuesday in the White House between Turkish President Abdullah Gul and U.S. President George W. Bush. (Writing by Gareth Jones and Thomas Grove; editing by Sami Aboudi)

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