WASHINGTON — President Barack Obama called his South Korean counterpart Lee Myung-bak to welcome the beginning of a long-delayed free trade agreement, the White House said.

Obama thanked Lee for "Korea's close cooperation in getting the agreement implemented," and stressed it was a strong example of the two country's partnership, the White House said in a statement, released on Wednesday.

The deal -- which goes into force at midnight March 15 in both countries -- was originally signed in July 2007 but was approved by the US Congress only last October after a partial renegotiation dealing mainly with the auto industry.

South Korea's parliament approved the free trade pact in November despite vehement protests from opposition lawmakers.

Supporters in both countries said the deal would strengthen economic and security ties between Seoul and its closest ally.

Two-way trade was worth $88 billion in 2010 and the US International Trade Commission has estimated that Korean exports to the United States would increase by $6.4-$6.9 billion annually.

Export-dependent South Korea already has trade deals in force with the European Union, India, Chile, Peru, Singapore and the European Free Trade Association (Liechtenstein, Iceland, Norway, and Switzerland).

Obama also told Lee that he was looking forward to his upcoming trip to South Korea later this month and expected a successful Nuclear Security Summit, amid simmering tensions with neighboring North Korea over its nuclear weapons program.