After days of sleeping outdoors with her two young children and hours of waiting in the strong sun for a bus out of Nepal's quake-devastated capital, Rajana's patience finally snapped.

"We've been left starving in the cold and the best this government can give us is this queue. Why are they so slow?" demanded Rajana as she lined up along with thousands of other Nepalis for a bus to her home village.

"I keep hearing on the news that all governments and aid agencies are here, but where are they? Our government is totally absent. Forget shelter, they couldn't even give us water," said Rajana, who goes by only one name.

Large areas of Kathmandu were reduced to ruins in Saturday's huge 7.8-magnitude quake that killed more than 5,000 people across Nepal.

Huge queues formed overnight in the capital after the government announced it was laying on free buses to take the city's weary residents back to their home villages.

Kathmandu's population has swelled dramatically in recent years, but many of its residents still regard their ancestral villages as home, and are desperate to return.

Old men leaning on walking sticks and wearing the traditional Nepalese topi hat stood patiently alongside tiny children whose parents feared for their safety in the devastated city.

"We've been staying in tents outside since the quake hit but it's a very difficult situation," said 35-year-old school teacher Humpasad Pokharel as he queued with his wife and their six-year-old daughter and baby son.

"Disease is starting to spread, and my children are not getting any clean water to drink."

- 'Safer in the village' -

Their Kathmandu house is still standing but the one beside it collapsed, killing all five people inside.

"They will be safer in the village," he said, gesturing to his family, who had been queueing since dawn.

Student Santosh Pandey was standing to one side of the queue with his 75-year-old grandmother, who had asked him to get her out of the city.

"She doesn't feel safe here any more," said the 23-year-old, as riot police armed with batons surrounded a group of men who had begun angrily protesting nearby over the lack of buses.

"When the quake hit I had to pick her up on my back and carry her out of the house. It was really scary.

"They said on the television there would be 500 buses here today, so we came, but we haven't seen any buses since we arrived. I don't know what will happen."

Lines of people carrying small suitcases and blankets, some with babies in their arms, snaked around the parliament building in central Kathmandu, where some residents made homeless by the quake had put up makeshift shelters.

Many appeared resigned to a long wait, but as buses failed to arrive after hours of waiting frustration mounted, a group of young men surged into the street, chanting anti-government slogans.

They began attacking vehicles, forcing them off the road and terrifying passengers.

"People are very angry," said 25-year-old accountant Bikash Niraula. "The government is weak and is not doing anything to help us."