Four U.S. warships have departed from the waters off Burma's coast after being denied permission by the country's military government to deliver relief supplies to the victims of last month's deadly cyclone.

USS Essex and the Essex Amphibious Ready Group steam in formation in the Andaman Sea, 23 May 2008

The USS Essex and its three support ships sailed away Thursday after three weeks docked off the Burmese coast. The ships were filled with 22 helicopters capable of delivering tons of supplies to the storm-ravaged Irrawaddy delta.

Burmese state media have said the government rejected the U.S. helicopters because it feared an invasion.

U.S. Admiral Timothy Keating says the ships will return if the ruling generals change their minds.

A 200-member emergency response team from the Association of Southeast Asian Nations (ASEAN) is heading to the delta to assess the damage caused by Cyclone Nargis, which left least 134,000 people dead or missing.

Despite its suspicion of foreign governments, Burma's government has accepted some outside support.

The White House says the U.S. has provided more than $26 million in assistance, and completed 106 airlifts of emergency relief. Other countries are also donating supplies.

But the United Nations says about one million Burmese still do not have food or water one month after the storm - half the number of people in need.

Meanwhile, Burma's most famous comedian has been detained by authorities after helping to deliver aid cyclone victims. A relative says Zarganar was arrested at his home in the main city of Rangoon Wednesday. The relative says police also seized some of the entertainer's compact discs.

Zargarnar was briefly detained last year after the military's bloody crackdown on anti-government protests.

Some information for this report was provided by AFP, AP and Reuters.