Sharply criticising the human rights record of four years of Pervez Musharraf's rule in Pakistan, the Human Rights Watch has demanded that the military ruler must stop harassment, torture and blackmail of political opponents, journalists and former government officials.

In a letter to President Musharraf on the fourth anniversary of his seizing power in a coup, the US-based human rights watchdog agency charged him with emasculating judiciary and marginalising mainstream opposition political parties and demanded he immediately restore democracy in the country.

The letter also blasted the Musharraf government for the continuing discrimination against women and minorities.

Raising concerns about Pakistan's collaboration with the United States in the 'so-called' war on terror, it said the cooperation has been exemplified by a 'disregard for due process.'

"Arbitrary arrests and detentions, allegedly with the support of the US authorities in Pakistan, have taken place with depressing regularity," it added.

The last four years have seen the rise in activity by extremist religious groups and an increase in sectarian killings, it said, adding that the military government's policy of marginalising political parties is partly to blame for it.

"Opposition legislators have told Human Rights Watch that they have been beaten, harassed and subjected to blackmail for opposing Musharraf's policies.

"In Pakistan, the judiciary has been emasculated, political parties rendered powerless, and extremist and sectarian religious parties strengthened under Musharraf's rule," said Brad Adams, executive director of Human Rights Watch's Asia division. "General Musharraf should transfer power to a legitimate government now."

The growing influence of extremist religious elements, HRW said, has impinged on the rights of women and religious minorities. Laws regarding rape and honour killings still discriminate against women.

"The number of blasphemy cases registered has risen while discrimination and persecution on grounds of religion persist. Adherents of the Shia branch of Islam have faced numerous violent attacks by Sunni Muslim militant groups," it added.