British Prime Minister David Cameron attends the first working session at the Commonwealth Heads of Government Meeting (CHOGM) in Valletta.
Valletta - David Cameron said sharing expertise would help defeat the "extremist scourge".
British Prime Minister David Cameron announced funding for a Commonwealth counter-extremism unit as the organisation's summit in Malta got under way on Friday.
Cameron, who joined other heads of government from the 53-country gathering for the first of three days of talks on the Mediterranean island, said sharing expertise would help defeat the "extremist scourge".
Combating radicalisation and extremist violence is one of the main issues expected on the table at the biennial summit.
French President Francois Hollande is due in Valletta, exactly two weeks after militant attacks in Paris, after attending a memorial event in the city for the 130 dead.
Cameron pledged $1.5 million a year over five years to establish and support a new Commonwealth counter-extremism unit.
It will be aimed at sharing expertise and identifying "new approaches to countering poisonous ideologies", his office said.
The unit will work through governments and civil society networks.
It will work in particular with Commonwealth countries struggling to deal with high numbers of foreign fighters and share technical counter-terror expertise, said Downing Street.
Pakistan and Nigeria in particular are dealing with violent extremists.
"The Commonwealth has a vital role to play in broadening international efforts to counter extremism," Cameron said.
"Its civil society and education networks make it particularly well-placed to complement international efforts to build counter narratives to this poisonous extremist ideology.
"This is the struggle of our generation, but by working together we will defeat this extremist scourge that is a threat to us all."
Cameron also held talks with Pakistani Prime Minister Nawaz Sharif on the sidelines of the summit as it started.
Maltese Prime Minister Joseph Muscat, who is hosting the summit, said of its counter-radicalisation talks: "I don't expect a solution; I expect more understanding.
"Around the same table we will have a mixture of countries not united by religion, race or region. So that facilitates a discussion on what can be done in order not to have more young people being lured by radicalisation," he said.
Muscat said young people were drawn towards extremism by the offer of "money and hope - something we should be offering them" instead, through employment and education.
"I expect some member states to announce initiatives that will be directly aimed at taking young people away from radicalisation and offering them alternatives."