Bangladesh has arrested an Islamist leader on charges of masterminding war crimes during the 1971 liberation struggle against Pakistan, lawyers say.
Prosecutors say that Ghulam Azam, 89, was detained after the International Crimes Tribunal (ICT) rejected his bail application.
They accuse Mr Azam of crimes against humanity - including murder, rape, arson and looting - in 1971.
He denies the charges, arguing that they are politically motivated.
Mr Azam, the former leader of the opposition Jamaat-e-Islami party, is alleged to have created and led pro-Pakistan militias which carried out numerous murders and rapes during the nine-month war.
"He was the mastermind of all crimes against humanity during 1971," state prosecutor Syed Haider Ali told the AFP news agency.
The ICT rejected the bail request made on health grounds by Mr Azam, a wheelchair user, and ordered him to remain in jail while awaiting trial, which is expected next year.
In November, another Jamaat-e-Islami leader, Delawar Hossain Sayedee, went on trial accused of crimes against humanity during the country's independence struggle.
Mr Sayedee was the first of seven suspects set to face a tribunal on charges relating to the 1971 war.
Charges listed against him include genocide, rape and religious persecution - all of which he denies.
Prosecutors say such trials are vital for the establishment of democracy in Bangladesh, which has yet to come fully to terms with its violent past.
The special court is trying Bangladeshis accused of collaborating with Pakistani forces, who were trying to stop Bangladesh becoming an independent nation.
It was set was set up in Dhaka in 2010 without any involvement by the United Nations.
It is not clear exactly how many people were killed. Independent researchers think that between 300,000 and 500,000 died, but the Bangladeshi government puts the figure at three million.
Correspondents say that Mr Azam is one of the most high profile Islamists to have been arrested since the nation's secular government set up the tribunal in 2010 to try suspects.
Two senior members from the main opposition Bangladesh Nationalist Party (BNP) are also facing war crime charges.
Both the BNP and Jamaat-e-Islami have dismissed the court as a government "show trial", a view supported by Human Rights Watch who recently said that its legal procedures fell short of international standards.
Mr Azam's lawyer, Abdur Razzak, strongly criticised his arrest, which came after he was called to appear before the tribunal.
"We don't know yet the charges against him, the order was not correct. He is also very old. Still, our bail petition was rejected," he said.
Bangladesh was called East Pakistan until 1971 when the nine-month war of secession broke out.
The trials of war crimes suspects are likely to go on for many months.