MONROVIA (Reuters) - Liberia s opposition Liberty Party will take its claims of election fraud to the Supreme Court this week after the electoral commission ruled on Friday that the first-round Oct. 10 vote was fair, it said on Sunday.  The appeal will likely set the West African country s presidential election back well into December, and could result in the first round poll being re-run, which could delay the first democratic transfer of power in over 70 years by months. Ex football star George Weah was meant to face Vice-President Joseph Boakai in a run-off vote in early November to determine who will replace Nobel Peace Prize laureate Ellen Johnson Sirleaf. But third placed candidate Charles Brumskine of the Liberty Party said the Oct. 10 first round was marred by widespread fraud, and the Supreme Court ordered the National Elections Commission (NEC) to investigate.  The NEC ruled last week that voting irregularities did not alter the outcome of the first round which Weah won with 38 percent versus Boakai with 29 percent. Brumskine won nearly 10 percent. International observers said the vote was largely free and fair.   We will take our case to the Supreme Court any time this week,  Brumskine told Reuters.  We were not surprised by the ruling. NEC were the defendants and judge at the same time.  The delay has raised tensions in Liberia where many say they are dissatisfied by Johnson Sirleaf s 12-year rule which cemented peace and brought much needed aid to the country after a civil war but which did little to alleviate dire poverty. The Liberty Party complained of widespread irregularities in the vote, including polling stations not allowing his supporters to cast their ballot. Under the constitution, it has until Friday to file its appeal, after which the Supreme Court has a further seven days to make a final ruling. 