MONROVIA (Reuters) - A presidential election run-off in Liberia scheduled for Tuesday will be delayed by a Supreme Court fraud investigation, the National Elections Commission (NEC) said on Friday. Former soccer star George Weah and Vice President Joseph Boakai are competing to succeed President Ellen Johnson Sirleaf, a Nobel Peace Prize laureate whose election in 2005 helped draw a line under 14 years of civil war. The vote is meant to mark Liberia s first democratic transition of power since 1944, but the Supreme Court this week halted preparations while it examined charges by third-place finisher Charles Brumskine s Liberty Party that the Oct. 10 first round was marred by fraud. Following arguments by the Liberty Party and counter-arguments by the NEC, Chief Justice Francis Korkpor said that the court would give its decision at 10 a.m. (1000 GMT) on Monday, one day before the scheduled poll.   The election will definitely be delayed, but we don t know for how long,  NEC spokesman Henry Flomo said.  The fact that the court will not rule until Monday is a delay.  Boakai s ruling Unity Party has backed the Liberty Party s allegations and even accused Johnson Sirleaf, one of its own members, of interfering in the vote by holding private meetings with election magistrates.  Johnson Sirleaf denied the meetings were inappropriate. Observers from the European Union and the Carter Center said they saw no major problems with the first round vote. Addressing the court s five justices, Brumskine cited  gross irregularities . In its complaint last week, the Liberty Party alleged various problems, including the late opening of polls, the absence of queue controllers and fraud by NEC officials.   This is not about losing or winning,  Brumskine told the court.  It has do to do with putting a system in place.  Lawyers for the NEC replied that the petitioners did not have any evidence and asked that the court lift its stay so that the commission could organize the second round.  The streets of the capital Monrovia remained calm with riot police deployed to protect the Supreme Court building and the election commission headquarters. Weah, who became the first non-European to win the European soccer player of the year award in 1995, won the first round of voting with 38.4 percent to Boakai s 28.8 percent. Brumskine won nearly 10 percent.  