Thousands of panic-stricken villagers fled their homes fearing flash floods after an overnight landslide blocked a river in quake-hit Nepal's mountainous northwest, officials said Sunday.

The landslide at around midnight sent mud and rocks tumbling into the Kali Gandaki river in Myagdi district, causing water levels to rise by 150 meters (490 feet), said local official Yam Bahadur Chokhal.

As he braces for the monsoon rains that threaten to inflict further misery after Nepal's devastating earthquake, Nawaraj Bista has more faith he will be safe inside his $100 quick-build corrugated iron home than under bricks and mortar.

Bista, a car salesman, saw his old home in Kathmandu reduced to rubble when a 7.8-magnitude quake ripped through the Himalayan nation on April 25.

Nepal Monday imposed a two-month moratorium on the start of new building projects and limited current construction to two storeys after recent deadly earthquakes destroyed nearly half a million homes.

Officials said the move would give authorities time to review building standards in the wake of a 7.8-magnitude quake on April 25 and a smaller one last week that reduced much of the capital Kathmandu to rubble.

A U.S. Marine Corps Osprey aircraft made a hard landing in Hawaii on Sunday, killing one Marine and sending 21 other people to hospitals as dark smoke from the resulting fire billowed into the sky.

The tilt-rotor MV-22 Osprey, which can take off and land like a helicopter but flies like an airplane, had a "hard-landing mishap" at about 11:40 a.m., the 15th Marine Expeditionary Unit said in a statement.

Nepal's prime minister on Sunday appealed for $2 billion to rebuild his country, shattered by two massive earthquakes in three weeks that have killed thousands and devastated the impoverished nation's infrastructure.

On April 25 a 7.8-magnitude quake, the deadliest to hit the country in more than 80 years, killed more than 8,500 people and destroyed half a million homes.

The Red Cross Saturday ramped up its appeal for aid to disaster-hit Nepal, requesting $93 million in assistance after two earthquakes in less than three weeks killed nearly 8,500 and left thousands homeless.

Relief teams have been working for weeks to provide water, food, shelter and medical assistance after the first, 7.8-magnitude quake hit on April 25, flattening whole villages and leaving thousands without shelter with just weeks to go until the monsoon rains.

The Nepalese army said Saturday troops had found the bodies of all eight people from the wreckage of a U.S. helicopter which crashed while delivering aid in the quake-devastated country.

The UH-1Y Huey was carrying six U.S. Marines and two soldiers from the Nepalese army when it went missing during a relief flight in the mountainous northeastern region on the same day that a second quake hit the country.

The U.S. military said Friday it did not expect to find any survivors after locating the wreckage of a helicopter that went missing with eight people on board in earthquake-devastated Nepal.

"I can confirm that we have located the wreckage... it is unlikely there are any survivors," said John Wissler, commander of the joint task force investigating the disappearance, three days after the chopper vanished while delivering aid in a mountainous region.

Nepal's prime minister said his government had been unprepared for the strong earthquake that hit two days ago, as he visited one of the areas worst hit by the disaster on Thursday.

Tuesday's 7.3-magnitude quake triggered landslides and brought down houses, bringing fresh misery to a country still reeling from an earlier massive tremor that left more than 8,000 people dead and destroyed half a million homes.

Krishna Prajapati's house in the historic Nepali town of Bhaktapur only just withstood last month's massive earthquake, but a second one this week proved too much for the weakened structure to take.

Just a day after his home collapsed on Tuesday, the 62-year-old was out salvaging bricks from piles of rubble the army had cleared from the streets of the devastated town to begin the grim task of rebuilding.