In a statement carried by the Anatolia news agency, police said the suspected members of the outlawed Kurdistan Workers' Party (PKK) were detained last week.

They were arrested in simultaneous operations in Istanbul and the neighbouring province of Kocaeli, in the country's northwest.

A search of the suspects' homes and cars led to the seizure of the explosives, 10 detonators and illicit documents, the statement added.

The suspects were planning to attack facilities in Kocaeli, the country's industrial heartland, ahead of Newroz, the Kurdish New Year, on March 21, the NTV news channel said.

Newroz has become an occasion for Turkey's Kurdish minority to demand greater freedoms or demonstrate support for the PKK. Celebrations have been marred by bloodshed in the past.

More than 37,000 people have been killed since 1984 when the PKK took up arms for self-rule in the mainly Kurdish southeast of Turkey.

The group, listed as a terrorist organization by Ankara and much of the international community, called a unilateral ceasefire on October 1 last year, saying it hoped to pave the way for a peaceful resolution of the conflict.

The truce, like previous ones called by the rebels, was rejected by Turkey but fighting has decreased markedly since then.