Britain's prime minister is expected to expand powers to combat terrorism in hopes of preventing attacks by Islamist militants returning for terror training in the Middle East.

David Cameron is unveiling a new package of legislation in the House of Commons on Monday. Talks with the Liberal Democrats, his partners in the governing coalition, stretched into late morning in hopes of finalizing a deal.

Measures under consideration include powers to take away passports from British citizens, though senior members of the Lib Dems have warned such measures may be illegal — even if they are temporary.

The moves come after Cameron pledged to plug gaps in Britain's defenses to combat terror, describing the extremist threat posed by the Islamic State group as being more dangerous than even that of al-Qaida.