WASHINGTON (Reuters) - The United States on Monday said it welcomed Mexico's entry into ongoing talks on a regional free trade agreement in the Asia-Pacific, but was silent about the status of Canada and Japan's bids to join the negotiations.

"We are delighted to invite Mexico, our neighbor and second largest export market, to join the TPP (Trans-Pacific Partnership) negotiations," U.S. Trade Representative Ron Kirk said in a statement after a meeting between U.S. President Barack Obama and Mexican President Felipe Calderon in Los Cabos, Mexico.

Kirk's office said the decision to invite Mexico into the talks was made with the eight other countries currently negotiating the TPP pact.

It said the Obama administration would shortly notify Congress of its intent to enter into negotiations with Mexico.

The nine countries currently negotiating the TPP are United States, Australia, New Zealand, Peru, Chile, Singapore, Malaysia, Vietnam and Brunei.

Canada, Japan and Mexico asked to join the negotiations in November.

(Reporting By Doug Palmer; Editing by David Brunnstrom)