Frustrations in the Colombian government continue to grow as its top soldiers are being recruited by the Middle East as mercenaries.

Defense Minister Luis Carlos Villegas said that Colombian soldiers are still needed in combat against drug traffickers and insurgents in the South American country, Bloomberg reported. Villegas also added that Saudi Arabia refused to discuss a treaty.

According to a former army officer with knowledge of recruiting contractors and a senior government official, a Saudi-led coalition battling in Yemen against Shiite Houthi rebels has deployed Colombian contractors, Bloomberg wrote. Soldiers are convinced to quit Colombia's army upon the termination of their enlistment with promises of wages seven times higher in the Middle East, the former officer added, who requested not to be named because he isn't allowed to publicly discuss the subject.

The ex-army officer revealed that an experienced Colombian soldier can get paid $90 per day in the Middle East, compared with around $375 per month in their homeland's regular army, Bloomberg further reported. Those who have officer rank and can speak English can earn $250 per day.

The former army officer also estimated that there are roughly 2,000 Colombians working as mercenaries in the United Arab Emirates, or U.A.E., adding that around 200 fighters are being sent to Yemen for tasks such as guarding bases. The troops haven't yet been deployed in combat.

Villegas said in a Dec. 22 interview in the capital, Bogotá, that Colombia's attempts at negotiating with Middle East governments have been futile.

"My complaint is why, for instance, the U.A.E. or Saudi Arabia have not been able to negotiate a treaty with Colombia to regulate that relationship," Villegas said, as quoted in Bloomberg's report. "Every time we approach those governments, the answer is no, we're not interested in a treaty."

With a treaty in place, Colombia could temporarily send instructors to the Middle East. This would be a preferred option than the current situation, whereby "someone in the underground of Bogota tries to reach our armed forces to see how 20 of our special forces can go undercover to the Middle East," he said, according to the news outlet.

When asked whether Colombia could solve the problem by giving higher wages to its soldiers, Villegas said, "I can't compete with Abu Dhabi," Bloomberg noted.

Colombian servicemen are deemed as one of the world's best fighters, Bloomberg added. Troops have fought in jungles and mountains for five decades against a guerilla insurgency. In an October operation, special forces hunted and killed Victor Ramon Navarro, also known as Megateo, a cocaine trafficker with a private army who controlled a mountainous area bordering Venezuela.