David Cameron is using a trade trip to South East Asia to discuss the threat of Isis spreading in Indonesia and Malaysia.
The Prime Minister will visit the two countries on a four day trip aimed at increasing trade with Britain.
In his meetings with Indonesian President Joko Widodo and Prime Minister of Malaysia, Najib Razak, Mr Cameron has said he will raise the threat of terrorism and its growing support in their countries.
In his recent counter-terror speech, Mr Cameron called the fight against Islamic extremism "the struggle of our generation".
The PM will offer assistance to counter extremism in the two countries such as disrupting foreign fighters and improving aviation security.
It is estimated that 500 people from Indonesia – which has the world's largest Muslim population – and 200 from Malaysia have gone to Iraq and Syria to join Isis.
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Ahead of his trip, the PM said: "Isil is one of the biggest threats our world has faced."
"We will only defeat these brutal terrorists if we take action at home, overseas and online and if we unite with countries around the world, unite against this common enemy."
"Last Monday, I set out what more we need to do at home to tackle this extremist ideology and build a stronger, more cohesive society."
"This week, I'll be talking to leaders in South East Asia about what they're doing to keep their country safe from these Islamist extremists."
"All of us face a threat from foreign fighters and from increasing radicalisation within our countries and it's right that we look at what help we can provide to one another."
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"I think Britain can offer expertise on practical counter-terrorism work - dealing with the threat from foreign fighters and investigating potential terrorist plots."
"And I think Britain can learn from Indonesia and Malaysia on the work they have done to tackle the extremist ideology and to build tolerant and resilient societies."
