LONDON, Dec 20 (Reuters) - British Prime Minister Boris Johnson said on Monday that he was looking at all kinds of things to keep the Omicron variant under control as the situation was extremely difficult, cautioning that further restrictions might be needed. "I have to say to the British public, and I say to everybody, we will not exclude the possibility of going further if we have to do things to protect the public," Johnson said after a cabinet meeting. "We will have to reserve the possibility of taking further action to protect the public." Asked about speculation that the government would ban indoor socialising and limit tourism, Johnson said: "I can certainly say we"re looking at all kinds of things... to keep Omicron under control and we will rule nothing out," Johnson said. Johnson said the situation was "extremely difficult" and that hospitalisations were rising steeply in London.