By William James
LONDON (Reuters) - Britain will introduce new laws on Tuesday to try to stop airlines carrying passengers who may be travelling to join Islamic State militants in Syria and Iraq, a junior minister said on Sunday.
Security services estimate some 600 Britons have gone to Syria or Iraq to join militant groups, including the man known as "Jihadi John" who has appeared in several Islamic State beheading videos.
Under the proposed new laws, Home Secretary Theresa May would be able to prevent airlines from carrying passengers, including children, believed to be travelling to take part in "terrorism-related activity" on known routes, such as those into Syria, according to a Home Office statement.
"This important legislation will disrupt the ability of people to travel abroad to fight and then return," James Brokenshire, a junior minister for security in May's department, said in the statement.
"It will also enhance our ability to monitor and control the actions of those who pose a threat," he added.
The rules would require airlines to seek permission to carry such passengers. An automatic system based on passenger lists provided by airlines would flag high-risk travellers and stop them boarding aircraft.
The new powers are part of Britain's efforts to stop foreign fighters from entering Syria via commercial flights and come weeks after three London schoolgirls fled Britain to join up with Islamic State through Turkey.
Turkish Airlines has previously said it was helping a government investigation into the case but that it was only responsible for checking visas.
Prime Minister David Cameron has also urged internet firms to do more to tackle online extremism after it was revealed the three girls had used Twitter to contact other women involved with Islamic State.
Speaking in an online chatroom on Sunday, Britain's Senior National Coordinator for Counter Terrorism, Helen Ball, said that at least 22 families in Britain had reported young women and girls as missing in the past year, believing that they had travelled to Syria.
(Editing by David Goodman and Clelia Oziel)