A group of British legislators is urging the government to remove the citizenship of Syrian President Bashar Assad's British-born wife.

Some Liberal Democrats in Parliament sent a letter to Home Secretary Amber Rudd on Sunday, saying Asma Assad should not be able to represent her husband and retain British nationality.

Lawmaker Tom Brake said: "The first lady of Syria has acted not as a private citizen but as a spokesperson for the Syrian presidency."

He said Asma Assad should either stop defending Syria's "barbaric acts" or lose her citizenship.

Britain has called for her husband to leave the presidency and condemned his use of chemical weapons.

Asma Assad was educated in Britain and worked as an investment banker before she married in 2000.