Nepal on Thursday recalled its ambassador to Qatar after she compared the Middle Eastern emirate to an "open jail" for thousands of Nepali migrants who face abuse from employers there.

Maya Kumari Sharma made the remarks six months ago to the BBC Nepali service, but they were reproduced on Thursday in a front-page investigation by Britain's Guardian newspaper into the deaths of Nepali migrants on projects connected to the 2022 World Cup in Qatar.

Nepal's Communication Minister Madhav Paudel told AFP that Qatar had complained about the comments of the ambassador, who was appointed by the former Maoist government a year and half ago.

"The government decided to recall Sharma because her dealings were not according to diplomatic decorum," Paudel said.

The Guardian investigation found that 44 Nepali migrants had died in just over a month during the summer in Qatar. It detailed how some had not been paid for months, were denied drinking water and had their passports confiscated.

"The overall picture is of one of the richest nations exploiting one of the poorest to get ready for the world's most popular sporting tournament," The Guardian reported.

Last month Sharan Burrow, the secretary general of the International Trade Union Confederation, warned that the majority of World Cup workers were likely to be South Asians who would encounter appalling working conditions in the "slave state".

World football body FIFA says it is consulting international labour groups on conditions in Qatar, while the desert state has promised reforms to its labour laws to offer greater protection to workers.

Hundreds of thousands of Nepalese go abroad every year to work, most of them in the Gulf or Southeast Asia. Qatar alone is home to about 300,000 Nepali workers, according to government figures.

In 2011 Nepal recalled its ambassador to Saudi Arabia after he was accused of stealing insurance money from the family of a migrant worker who died there.