TIRANA, April 21 (Xinhua) -- "Gulf" oil company, one of the biggest oil firms in Albania, is under investigation for fraud scheme of selling coupons worth 1.5 million euros (1.85 million U.S. dollars)a few days before closing its activity, local media reported on Saturday.

Tirana prosecution office is investigating. The main suspect is the company's manager Albano Aliko who is suspected of the fraud scheme.

The prosecution suspects that "Gulf" has intentionally sold more oil than the company owned through coupons. The company may have gathered 1.5 million euros by selling worthless coupons to their customers.

Some businesses have prepaid up to 3,000 liters of fuel and left unused paper pieces in their hands.