Foreign fighters are not responding to Islamic State calls to head to Libya rather than Syria or Iraq, the UK Government has claimed.
Middle East Minister Tobias Ellwood said he believes the terror group has up to 6,000 extremists in Libya, with the "vast majority" foreign fighters rather than Libyans.
But he attempted to play down suggestions that IS, also known as Daesh, is bolstering its fighting force with new foreign recruits in the north African country rather than its existing strongholds.
United Nations experts believe the political and security vacuum in Libya is being exploited by IS, reporting it has "significantly expanded" the territory it controls in the nation and become "increasingly attractive to foreign fighters".
They noted, in a report to the UN Security Council released last week, that fighters mainly used Sudan, Tunisia and Turkey to reach Libya in 2014 and 2015.
Mr Ellwood, responding to a written parliamentary question, said: "Our current estimate for the number of Daesh fighters in Libya is between 3,000-6,000.
"We do not have earlier estimates from which we could extrapolate a trend. The vast majority of Daesh fighters in Libya are foreigners rather than Libyans.
"While some Daesh figures have called for foreign fighters to go to Libya rather than Iraq/Syria, we have not seen any evidence to suggest this has happened."
Mr Ellwood said US estimates suggest there are approximately 19,000 to 25,000 IS fighters in Iraq and Syria compared to 20,000 to 31,000 in 2014.
Defence Secretary Michael Fallon announced last month Britain would send 20 troops to Tunisia to help prevent IS extremists entering the country from Libya.
He has also offered to provide training and advice to support a new Libyan government although stated he does not intend to deploy British troops in "any combat role" in Libya.
US president Barack Obama has criticised European nations, including the UK, for failing to prevent Libya becoming a "mess" in the aftermath of the 2011 war to counter then dictator Muammar Gaddafi.