Prime Minister Gordon Brown has announced a ban on direct flights from Yemen to the UK.
The ban comes amid security fears following the attempted bombing of a passenger plane on Christmas Day by a man allegedly radicalised in Yemen.
In a statement to the House of Commons, Mr Brown also announced the creation of two new terror watch lists as part of a package of measures aimed at beefing up border security.
Umar Farouk Abdulmutallab, who attempted to detonate explosives on the plane as it came in to land in Detroit, was a student in London but came into contact with al Qaida in Yemen.
Mr Brown said the ban on direct flights would remain in place until new security measures were put in place in the Middle Eastern country.
Yemen was an "incubator and potential safe haven for terrorism", he added.
One new list will contain the names of individuals prohibited from flying to and from the UK. The second, longer list will include lower risk individuals who will be subjected to special screening before they can board planes heading for the UK.
The PM also pledged that all major ports and airports would be covered by the Home Office's e-borders scheme by the end of this year.
Under the £1.2 billion programme, passengers must provide detailed personal information when buying their tickets so they can be checked against watchlists before flying.
Mr Brown said: "We have agreed with Yemenia Airlines - pending enhanced security - that they suspend their direct flights to the UK from Yemen with immediate effect. We are working closely with the Yemeni government to agree what security measures need to be put in place before flights are resumed. I hope that flights can be resumed soon - but the security of our citizens must be our priority."
