More than 100 Peace Corps volunteers have left Kazakhstan, after the US organisation announced an abrupt end to its programme.

The Peace Corps cited "organisational considerations" as the main reason for halting its programme after 18 years.

Some reports have suggested the pull-out was prompted by security concerns and a rising number of sexual assaults.

The Kazakh authorities said it was a logical step as the country is not poor and does not require such help.

The volunteers, who had been working in different parts of the vast country, were summoned to Almaty and sent home over the weekend.

The organisation has not given an explanation for its departure.

Volunteers' concerns

But blogs written by volunteers suggested it was the rising number of sexual assaults and security threats that had prompted the Peace Corps to wrap up its programme.

One volunteer, who did not want to be identified, told the BBC she was sexually assaulted after moving from a village to a larger city.

Apparently, a request to move volunteers from rural to urban areas was made by the Kazakh authorities a year ago.

But the authorities deny such a request was made. Instead they agree with the Peace Corps decision to leave, calling it a logical step because of the country's significant political and socio-economic progress.

However, some returning volunteers have painted a different picture about Kazakhstan's pace of development.

"I wish that people like the government ministers here could take a minute to step outside their office building, to step on a train and really go to some of the poorer places, where volunteers serve," said one volunteer.

"Because in those places there is no running water, schools are not heated, the children need information about teeth brushing because their teeth are rotting out of their heads - these are very basic things."

Kyrgyzstan and Turkmenistan are now the only countries in the Central Asia region with a Peace Corps presence.