FILE PHOTO: Prime Minister of Bangladesh Sheikh Hasina waves to the media after her visit at the ancestral house of the Indian poet Rabindranath Tagore in Kolkata, India, May 25, 2018. REUTERS/Rupak De Chowdhuri/File photo

DHAKA/MUMBAI (Reuters) - The death toll in a Bangladeshi “zero tolerance” crackdown on drugs has risen to 140, with about 18,000 people arrested, the government said on Thursday, as a group of activists urged the United Nations to step in to stop the bloodshed.

Prime Minister Sheikh Hasina approved the anti-narcotics campaign in early May to tackle the spread of methamphetamines but the killings have raised fears among rights groups of a bloody Philippine-style campaign to wipe out drugs.

“In a manner reminiscent of the Philippines drug war, Bangladeshi police justified these killings as supposedly happening during ‘gunfights’ with rival gangs or law enforcement officers acting in self-defense during anti-drug operations,” the International Drug Policy Consortium said in a statement, urging U.N. agencies to act.

“Evidence worldwide have shown that such a violent and abusive approach has not managed to curb the illicit drug market, but it can be used as a political tool to win political elections and target unwanted opposition,” said the consortium of nearly 200 non-governmental organizations.

Their call joins a chorus of international pressure on Bangladesh to stop the violence, which a home ministry official told Reuters had claimed 140 lives, with some 18,000 under arrest.

The war on drugs in the Philippines has killed thousands since President Rodrigo Duterte took office two years ago. Duterte won a landslide victory after vowing to crack down on what he called the “drug menace”.

Hasina, who faces a general election later in 2018, has dismissed accusations of extra-judicial killings, and said the crackdown enjoys popular support.

The U.N. High Commissioner for Human Rights Zeid Ra’ad al-Hussein on Wednesday called for independent investigations into the killings and said there was a “high likelihood” that many people may have been arbitrarily detained.

The consortium also asked the United Nations to advise Bangladesh against bringing in the death penalty for drug-related offences, which is under consideration in the South Asian nation.