GEORGETOWN, Guyana (AP) — The election commission in oil-rich Guyana has declared that the governing coalition won the country's disputed vote, despite international concerns about the credibility of the process.

The commission said late Friday that it will move this weekend to verify vote totals in the March 2 general election as international observer groups said the tallying was flawed and not transparent.

Barring any successful court challenges, the governing coalition led by retired army Gen. David Granger, 74, would begin a second five-year term in office. Coalition officials said they plan to swear in Granger on Monday.

Joseph Harmon, a campaign manager of the governing coalition, appealed for calm and said the government hopes that the "country can return to normal."

“Not a single finger has been lifted against the president and the coalition regarding fraud,” Harmon said. “The people of Guyana came out based on the message from our campaign.”

However, the main opposition People’s Progressive Party, or PPP, led by former housing minister Irfaan Ali, along with some observer groups have complained about their inability to verify numbers provided by election officials.

An observer team from the Washington-based Organization of American States, headed by former Jamaican prime minister Bruce Golding, withdrew from the monitoring process on Friday and said its final report in the coming weeks will reflect dissatisfaction with the system. It earlier called for an abandonment of the manual, vote-tallying system because of its vulnerabilities to fraud.

The U.S. and several other Western ambassadors who were monitoring the counting as accredited observers also walked out of the counting late Friday, saying they were unhappy with the lack of a verification system.

In a statement, the ambassadors warned that a president sworn in under a process deemed to be flawed could not be considered legitimate.

“The betterment of Guyana and its people has always been our interest. In that spirit we urge all parties to not do anything which could lead to Guyana’s isolation,” the ambassadors said.

The final tallying process was held up by disputes over results for a district including Georgetown, the capital, and nearby areas. Whichever political group wins this key district by at least 40,000 votes is usually the winner of the national election. The results released overnight Friday gave the governing coalition 136,057 votes for the district and 77,231 to the PPP, amounting to a coalition lead of two seats over the opposition in the 65-seat congress.

The election dispute comes as the South American country of fewer than 1 million people faces the prospect that oil revenues in the next decade could make it one of the wealthiest in the hemisphere.

Guyana recently sold its first million barrels to markets in Asia and southern U.S. states. It will get four more shipments this year worth about $300 million as part of production-sharing arrangements with a consortium led by ExxonMobil, along with Hess Oil of the US and Nexen of China.