LONDON (Reuters) - Britain said it would boost its "hollowed out" armed forces to make sure the country was prepared to face what the head of a defence review called a "deadly quartet," comprising China, Iran, North Korea and Russia.

The government named George Robertson, the former NATO secretary general, on Tuesday to lead a review of Britain's armed forces which will report back in the first half of 2025.

Robertson, a former British defence minister in the late 1990s who ran NATO from 1999 to 2003, said the armed forces needed to be battle ready given the threat level.

"We’re confronted by a deadly quartet of nations increasingly working together, and we in this country, and the NATO alliance that met so successfully last week, have got to be able to confront that particular quartet as well as the other problems," he told British media.

Prime Minister Keir Starmer reconfirmed his commitment to lifting defence spending to 2.5% of GDP at a NATO summit in the United States days after he was elected, although he is yet to say when that will happen.

Launching the review, Starmer, describing the armed forces as "hollowed out," said he wanted to responsibly raise spending to ensure long-term resilience.

Robertson said: "The NATO summit last week in Washington made it perfectly clear that the challenge of China was something that had to be taken very, very seriously indeed."

Fiona Hill, a former U.S. presidential adviser and foreign policy expert, would also oversee the review, with retired British Army officer, General Richard Barrons, who was formerly Commander of the Joint Forces Command.

(Reporting by Sarah Young; Editing by Bernadette Baum)