GEORGETOWN, Guyana (AP) — Guyana’s government Thursday refused to suspend use of the Russian Sputnik-V vaccine despite opposition warnings that doses could be fake and acquired through third party suppliers at higher than normal prices.

Opposition leader Joseph Harmon demanded a halt to the use of the Russian-made vaccines that he said were acquired from a United Arab Emirates businessman Sheikh Ahmed Dalmook Al Maktoum instead of directly from suppliers in Russia.

Harmon said he fears for the authenticity of the vaccines, pointing to international reports linking the the sheikh to a Norwegian businessman and allegedly dubious sales of the vaccines to developing countries.

Harmon also pointed to what he said were fake doses being discovered by authorities in Mexico and Africa. He called for the program to be suspended until a full verification exercise is undertaken to ensure those being administered here are the real thing.

“We demand that these vaccines be put on hold until the population is given an assurance that what we are dealing is not a bogus transaction and that we are dealing with safe arrangement,” Harmon, an attorney, said.

Health Minister Dr. Frank Anthony defended the vaccine acquisitions, saying Russian government officials had pointed him to international contract suppliers of the doses and so far the arrangements with the sheikh have been positive and reliable.

“We have a contract with them and so far they have been delivering,” Anthony said at a briefing. “We are disappointed that the leader of the opposition believes that the price Guyana paid for Sputnik V vaccines is overpriced. Guyana has sought to procure directly from the Russian Sovereign Fund, but with no firm commitments on a delivery schedule, Guyana opted to utilize a supplier. It was a good investment for our people at the time. It remains a good investment at this time."

He argued the statement by the opposition leader could further hamper efforts to beat vaccine hesitancy, noting that not one of 10 administrative regions in the country has seen vaccination rates above 55 percent. In one region just south of the capital, only 14 percent of the population have opted to take jabs.

“At no time did Guyana procure vaccines from any illegal entity or anyone in trouble with legal authorities anywhere," Anthony said. "Guyana has not procured vaccines from any illegal source as far as Mr. Harmon’s claim that the government procured vaccines from any international fraudster. This is blatantly false.”

More than 440 COVID-19 deaths have been recorded in Guyana since the first in March of last year.