PARIS (Reuters) - North African countries should be cooperating more to stop Islamic State fighters who are fleeing their Libyan stronghold of Sirte from returning to their homelands and causing trouble there, Tunisia’s defense minister said on Tuesday.

Libyan forces aligned with the U.N.-backed government in Tripoli launched their campaign to recapture Sirte in May and are advancing on the last areas under its control.

But Tunisia, which estimates that about 4,000 of its nationals left to fight for jihadists groups, is concerned that many are returning to the country and could turn their focus on home soil.

“The danger is real. Those who leave Sirte are heading south to eventually join Boko Haram, but some are also going west,” the Tunisian minister, Farhat Hachani, told journalists on the sidelines of a gathering of defense and military officials in Paris.

“There isn’t a regional strategy. Neighboring countries are managing the day to day security and military question ... but while there are terror laws, you need proof that a young person was in a camp or fighting in jihadist ranks,” he said.

International cooperation is “not up to the level of the danger”, he added. “We are in a decisive moment. The threats endanger all the region. We have to cooperate before the boat sinks.”

His French counterpart Jean-Yves Le Drian said the spread of militants beyond Libya had to be dealt with and a plan put in place.

“They don’t just disappear so there’s a new risk there and only a real cooperation between all neighboring countries will enable us to face that threat,” Le Drian said.