Sri Lanka has hired two hangmen as it prepares for the executions of four prisoners convicted of drug offences in what will be the country's first use of the death penalty for over 40 years, prison authorities say.

Key points: The two were picked from among 100 applicants who responded to an advertisement

The two were picked from among 100 applicants who responded to an advertisement President Maithripala Sirisena has announced an end to a moratorium on the death penalty

President Maithripala Sirisena has announced an end to a moratorium on the death penalty Local and international rights groups have raised concerns about the restoration of capital punishment

The Department of Prisons began the recruitment process in March after the last hangman quit in 2014, citing stress after seeing the gallows for the first time.

Another, hired last year, never turned up for work.

President Maithripala Sirisena last week announced an end to a moratorium on the death penalty in force since 1976, a move political analysts said was meant to boost his chances of re-election if he stood again later this year.

Local and international rights groups, along with Britain, Canada, the European Union and United Nations have raised concerns about the South Asian nation's restoration of capital punishment.

"The recruitment process is finalised and two [hangmen] have been selected," prisons spokesman Thushara Upuldeniya said.

"The two need to go through final training which will take about two weeks."

The two were picked from among 100 applicants who responded to an advertisement calling for male Sri Lankans aged between 18 and 45 with "excellent moral character" and "mental strength".

Prisons Commissioner TMJW Thennakoon declined to provide details of the four criminals whose death penalties were approved by the President.

On Friday, a petitioner — a Sri Lankan journalist — filed public interest litigation seeking to stop any executions, arguing that people's rights were being violated.

A court hearing will be held on July 2, and Mr Thennakoon has pledged there will be no executions for the next seven days.

Job advertisements for the hangmen positions were placed in newspapers earlier this year. ( Reuters: Dinuka Liyanawatte )

A spokesman for the United Nations Office on Drugs and Crime (UNODC) said international drug control conventions could not be used to justify the use of the death penalty for drug-related offences alone.

"Application of the death penalty may also impede international cooperation in fighting drug trafficking as there are national laws that [bar] the exchange of information and extradition with countries which may impose capital punishment for the offences concerned," the UNODC spokesman said.

Reuters