Hasina's lawyers served a legal notice on British Airways (BA) on Friday after the airline refused to let her board the April 23 flight to Dhaka, her secretary told AFP.

"BA did not give her a boarding pass, citing security reasons. It caused her immense mental stress and agony," Abdus Sobhan Golap said from London.

"We are seeking a million pounds (two million dollars) in damages," he said, adding that BA has two weeks to reply to the notice.

There was no immediate comment available from British Airways.

The Bangladesh government blocked Hasina's return from London on April 18, saying she was a national security threat.

Last Wednesday, the government said it was lifting restrictions on her return, backtracking on plans to exile her and her bitter rival Khaleda Zia amid local and international pressure.