Turkish police are often criticised for beating protesters

Evidence extracted under torture is often used and some people are being held on remand for more than a decade, the group adds.

Amnesty called the trials a blight on Turkey's human rights record.

Separately, Europe's human rights watchdog has said in a report that torture of prisoners in Turkey is declining but remains a problem.

Reform of the judiciary is a key area in the talks Turkey began last October to join the European Union.

In 2004 the country introduced Heavy Penal Courts to replace the much criticised system of State Security Courts.

However, Amnesty's report says that the new special courts still admit past evidence extracted under torture and are staffed by judges who had been hearing the same cases under the old system.

'Encouraging signs'

The report released by the Council of Europe's anti-torture committee says that there are "encouraging" signs that Turkey is enforcing its new policy of stamping out abuse of prisoners.

The Strasbourg-based human rights body reached its conclusions after a fact-finding mission in Turkey last year.

A European delegation interviewed many people who had been in police custody.

"The great majority of those persons stated that they had not been physically ill-treated whilst in custody," the report said.

But abuse was still a problem, particularly in police stations, the European organisation said, quoting allegations of torture in three Turkish provinces - Adana, Istanbul and Van.