DHAKA, BANGLADESH - Bangladesh police arrested an opposition politician Thursday on murder charges, a day after he was named a suspect in an unrelated war crimes investigation into the country's 1971 liberation struggle.

Salauddin Quader Chowdhury, a key figure in the main opposition Bangladesh Nationalist Party (BNP), is accused of war crimes during the nine-month struggle against Pakistan which left three million dead according to official estimates.

He was arrested at his residence in the capital, Dhaka, in connection with a murder case in June this year, deputy commissioner of police Monirul Islam said, without giving further details.

"He has not been arrested in connection with any war crimes related cases," Islam told AFP.

In Bangladesh, it is routine for police to arrest suspects on one charge and then add multiple cases against them while they are in custody.

In July, the leaders of the country's main Islamic party, Jamaat-e-Islami, were arrested for "offending public religious sentiment" and then subsequently charged with war crimes.

The war crimes tribunal on Wednesday said they had found concrete evidence of Chowdhury committing war crimes such as genocide, rape, arson and looting during the war, and charges on these cases are likely to follow.

The tribunal was set up in March to try people suspected of atrocities during the campaign for independence from Pakistan led by Sheikh Mujibur Rahman, Bangladesh's founding father.

The BNP and Jamaat have dismissed the tribunal as a political show trial. Bangladesh, which was part of Pakistan until 1971, has struggled to come to terms with its bloody birth.

A private group that has investigated the conflict has identified 1,775 people, including Pakistani generals and local Islamists, as complicit in the atrocities.