Cyprus' support for Britain's air campaign against the Islamic State group in Syria and Iraq has been essential in sustaining almost 3,000 combat missions so far this year, Britain's defense secretary said Tuesday.

Michael Fallon said the Royal Air Force hasn't kept such an operational tempo in a single theatre of conflict in more than 25 years.

Britain maintains two military bases on Cyprus — including Akrotiri, from where anti-IS group missions are being flown.

Fallon said it would be "much harder to sustain" so many missions, which included 948 air strikes in Syria and Iraq, without the help of Cyprus. The country's eastern shores are 100 miles (160 kilometres) from the Syrian coastline.

"Only the U.S. is doing more," Fallon said after talks with Cypriot counterpart Christoforos Fokaides, adding that IS group "is losing land, losing money, losing the fight."

Fallon said the air campaign has helped push the Islamic State group out of 40 percent of the territory it had taken since 2014.

"Britain is determined to keep pulling out all the stops in this fight against evil," he said.

Fallon also offered assurances that British voters' decision to leave the European Union in a June referendum doesn't mean that the country will "abandon European security."

He said Britain would accelerate the fight against IS, step up efforts to counter illegal migration and build stronger security ties with Cyprus, an EU member. Britain will take part in the coming months in joint search and rescue exercises.