Pakistan has tightened its anti-terrorism laws, allowing police to detain suspects for up to a year without bringing charges.

The amendment to the law, which has come into immediate effect, also allows police and security forces to investigate the assets and bank accounts of relatives of any suspects.

Musharraf: Waging own war on terror

Human rights campaigners have attacked the new move as draconian.

Pakistani President Pervez Musharraf has supported America's war on terror despite some opposition within the country.

He has made a crackdown on extremism a priority for his government.

Militants have carried out several deadly attacks in the country, including the bombing of Karachi's Sheraton Hotel in May which killed 11 French nationals and three Pakistanis, and an attack on the US consulate in June in which 12 people died.

The amended law was issued on Sunday after being approved last month by General Musharraf's cabinet.

Law 'unjustified'

It allows the government to order the arrest of suspects and extend their periods of detention without charge for up to 12 months.

Human rights groups are concerned about the fate of Dr Aziz

If released on bail, suspects would be banned from visiting public places such as cinemas, airports and hotels.

The law also extends police powers to the arrest of anyone suspected of ties to groups involved in sectarianism which have not been banned.

Suspects will have the right to challenge their detention in court, which will then be given 30 days to come to a decision.

But Kamila Hyat, joint director of the Human Rights Commission of Pakistan (HRCP), said that the law would solve nothing.

"This is totally unjustified," she said. "Draconian laws such as these do not solve the problem of either militancy or terrorism. They only increase the feeling of injustice and victimisation."

Ms Hyat said the HRCP was concerned about the fate of Aamir Aziz, a medical doctor suspected of having links with the Taleban.

Dr Aziz was arrested on 21 October and his whereabouts are still unknown.

A Lahore High Court judge has given the government until Tuesday to find the doctor, who is thought to be in the custody of the military intelligence service, the ISI.

The court is due to hear two petitions challenging the undeclared detention, including one from Dr Aziz's mother.