UPDATE 1-Japan agrees to relax U.S. beef import restrictions

* Govt panel of medical, food experts approve step

* Move from Feb will allow imports from cattle older than 20 mths

* U.S. beef exports to Japan dropped by 60 pct over past decade

TOKYO, Jan 28 (Reuters) - Japan on Monday agreed to allow U.S. beef imports from cattle up to 30 months old from February, relaxing a restriction in place for about a decade on what was once the biggest market for U.S. exports.

Under rules imposed in 2005, U.S. beef imports had only been allowed from cattle up to 20 months old after a total ban in 2003 following an outbreak of bovine spongiform encephalopathy (BSE). The restrictions helped Australia boost its share of Japan's 500,000 tonnes-a-year imported beef market.

Raising the age restriction, which had been mulled since 2011 as concern over mad cow disease ebbed, will allow U.S. exporters such as Cargill Inc and JBS USA Holdings Inc to regain lost market share in the world's No.2 beef importer.

U.S. meat exporters say the step brings Japan into line with other countries.

But the Consumers Union of Japan said on Monday that it opposed the move due to concerns over lax checks on animal feed and product shipments in the United States, adding that Japan's government had underestimated the risks involved.

A government panel of medical and food experts agreed to relax the restriction after Health Minister Norihisa Tamura left the decision to the panel. Tamura has said it would become effective on Feb. 1 upon the panel's approval.

A health ministry official said Japan and the United States had agreed to keep talking about further loosening regulations longer term.

The country's imports of U.S. beef plunged by 60 percent to some 120,000 tonnes from 2001 to 2011, with Australian suppliers the main beneficiaries in an import market worth over $2 billion.