South Korea and the United States have failed to reach an agreement on revising a pending free trade pact before the opening of the G20 summit in Seoul.

Trade Minister Kim Jong-hoon said the two countries were unlikely to reach an agreement before the start of the summit Thursday evening.

He said he reported to President Lee Myung-bak that unreasonable demands by the U.S. have made it difficult to come to a compromise on a revision of the agreement.

The president reportedly ordered that additional negotiations be held after the completion of the G20 summit on Friday.

The two countries had planned to wrap up negotiations and announce the results of trade talks at a South Korea-U.S. summit on Thursday, just hours before the opening of the G20 summit.

Seoul and Washington reportedly remain wide apart on issues related to the auto and beef sectors.