The HRCP fears the government will become less tolerant of critics

Akhtar Baloch, the Sindh province co-ordinator of the Human Rights Commission of Pakistan (HRCP) disappeared in Hyderabad after a commission meeting on Sunday.

The authorities in Sindh have made no public comment on the case.

Journalists and co-workers have staged protests in Sindh calling for his release.

Linked to report?

Commission director IA Rehman told the BBC that Pakistan was in danger of becoming a "Gestapo state" if such disappearances were to go unchecked.

Mr Rehman said the detention could be linked to a recent commission report on human rights in Pakistan.

Inquiry call

"It could be one of two things. Either the government wants to send a message to the HRCP - 'we can do this to you' - or the local authority in Sindh has developed a grievance because of his work," Mr Rehman said.

This is not an isolated affair. There are other cases - such as doctors - who have been detained IA Rehman

Mr Baloch's work in Sindh includes investigating disappearances and extra-judicial killings.

Mr Rehman said the government had not tried to interfere with the work of the commission, but added: "Pakistan is not what it was one year ago... Now there is more pressure from the opposition and in this situation the establishment will become less tolerant."

He said the commission had demanded an inquiry by judicial authorities into the detention but said the HRCP might hold its own public inquiry if unsatisfied.

Mr Rehman added: "This is not an isolated affair. There are other cases - such as doctors - who have been detained."

Critical report

Former commission chief Asma Jahangir told the BBC it had been told "informally" that Mr Baloch was picked up by a government agency and he would be released soon.

The detention came after a report critical of President Musharraf

The HRCP said it had been "advised" not to use the name of any agency "irresponsibly".

Last week the HRCP published a report on human rights in Pakistan in 2002.

It said there had been some advances in human rights, such as the greater representation of women in parliament.

However, it said President Pervez Musharraf had shifted power to the unelected presidency and a military-dominated National Security Council in a series of "fundamentally flawed" moves.

The general seized power in a bloodless coup in 1999.

Pakistan's Information Minister, Sheikh Rashid Ahmed, dismissed the criticism. He said General Musharraf had stuck to the internationally agreed timetable for democracy to the day.

The fact that the opposition was attacking the government in full force, he said, was testimony to Pakistan's functioning democracy.