By Susan Cornwell

WASHINGTON, May 20 (Reuters) - Myanmar's response to Cyclone Nargis has been "appalling" and its junta will be responsible for a second disaster if it does not admit more aid and relief workers, a senior U.S. diplomat said on Tuesday.

More than two weeks after the cyclone hit, the military government's failure to provide greater access to the stricken region is putting hundreds of thousands of lives at risk, said Scot Marciel, the U.S. envoy to Association of Southeast Asian Nations (ASEAN).

"The door must be opened far wider -- and rapidly -- to prevent a second catastrophe," Marciel told a congressional hearing on the disaster in the former Burma.

"The Burmese regime's response to this disaster has fallen short of what was required. Frankly, it has been appalling," Marciel told a U.S. House of Representatives Foreign Affairs subcommittee.

The junta gave priority to a "deeply flawed referendum" on an army-drafted constitution days after the storm, rather than focusing on the humanitarian disaster, he said.

"If assistance is not allowed in, and thousands of Burmese perish, the responsibility for this catastrophe will fall squarely on the shoulders of Senior General Than Shwe and other Burmese leaders," he said.

Marciel, who is also a deputy assistant secretary of state, was named earlier this month as the first U.S. ambassador to ASEAN, a regional group of which Myanmar is a member.

He welcomed the group's plans to convene an aid pledging conference on Sunday in Myanmar's capital Yangon, where it will work on a bigger aid delivery plan for Myanmar. Nearly 134,000 are dead or missing and 2.4 million have been left destitute.

Myanmar has allowed relief flights to deliver supplies to Yangon but balked at allowing aerial access to the southwestern delta, which bore the brunt of the storm.

Washington was still reviewing whether the United States would participate in the pledging conference, Marciel told reporters after the hearing.

For any additional aid that is pledged to be really effective, it should be "needs-based," which required increased access for international relief workers, Marciel stressed.

The U.S. Agency for International Development has provided over $17.5 million in assistance to Myanmar, the agency's Gregory Gottlieb told the House subcommittee. Other amounts had been channeled through the Red Cross and other organizations.

With the cost of supplies and funds to the Pentagon for flying in the aid, U.S. government humanitarian assistance as of Monday was over $30 million, said Gottlieb, the deputy assistant administrator in the bureau for democracy, conflict and humanitarian assistance at USAID.

There have been 36 U.S. C-130 transport plane flights into Yangon with aid, he said. At first the junta insisted on taking control of the aid as soon as it landed, but since May 16 the United States has been handing over supplies directly to non-governmental organizations, he said. (Editing by Anthony Boadle)

AlertNet news is provided by