Lord Cameron has accused Labour of standing for nothing after Sir Keir Starmer accepted a right-leaning Tory MP into the party.

The foreign secretary said Sir Keir welcoming Dover MP Natalie Elphicke into Labour on Wednesday showed the party does not have a plan. "In life, if you don't stand for something, you will fall for anything," he said following a speech about defence on Thursday.

"I thought that's sort of what yesterday said, that there isn't a policy about anything. "It's just been about clearing the decks to try and focus attention on the governing party.

"And I think yesterday proved, 'oh, if you're going to fall for that, then you really stand for nothing'. The plan, policies? No idea." "When you hear about a defection you think 'oh no, not another one, how are we going to handle this by the end of the day?'.

"But that says so much more about Keir Starmer, the Labour Party, and a complete lack of clarity than it does about a prime minister who's a good man, doing a great job in a difficult time," he said. "But I think increasingly people will see that." Mrs Elphicke's defection has been criticised on all sides of the political spectrum, with many Labour MPs unhappy to have a politician in their party who was seen as being to the right of the Tory party, especially with her views on immigration.

Conservative MPs have expressed their confusion over why she defected after heavily criticising Labour on many occasions. Lord Cameron was giving a speech on the UK's national security at the National Cyber Security Centre when he made the comments.

He called on Britain and its allies to "out-compete, out-cooperate and out-innovate" their adversaries in an ongoing "battle of wills". Too many "adopt a kind of defensive crouch" instead of taking action, but Britain can choose to make a difference together with its partners, he said.

Read more:Former chancellor and vaccines minister to stand down at general electionA defection and an intervention show the Tory party is splintering "We in Britain and the wider West have agency - the question is if we have the courage to use it - the courage to act," he said. He added that the UK will not sign free trade deals "for the sugar rush of the press release".

In the wide-ranging speech, he also defended the government's deal to send asylum seekers to Rwanda, saying the UK was open to the world - but would not allow criminal gangs to decide who can enter the country. He also reiterated the recent UK commitment to build up to spending 2.5% of GDP on defence and said other Nato allies should be aiming for this too.

"Still some seem unwilling to invest even as war rages on our continent," he said..