LONDON – The head of Britain’s MI5 domestic security service said Monday that Britons face a “serious and sustained threat” of terror attacks at home and abroad.

Eliza Manningham-Buller said Osama bin Laden’s al-Qaida network can still mount attacks, despite the arrest and killing of many of its senior leaders.

The terrorist group has also inspired other militants, she said.

“There is a serious and sustained threat of terrorist attacks against UK interests at home and abroad, including against the business community,” Manningham-Buller told the Council of Business Industry annual conference in London.

“There might be major attacks like Madrid earlier this year. They might be on a smaller scale,” she added.

“The terrorists are inventive, adaptable and patient. Their planning includes a wide range of methods to attack us.”

Manningham-Buller has repeatedly warned that the al-Qaida network was resilient and that the threat of attack by Islamic terrorists would remain for “a long time.”

She said Monday that counterterrorism has helped to prevent attacks in Britain since the Sept. 11, 2001, attacks in the United States.

“Responding to the threat has not been easy, and difficult judgments have to be made,” she said. “Balancing liberty against security is perhaps the most difficult of them.”