Neighbors say when three men kicked down the doors and burgled the home of a North Korean diplomat in Islamabad last month, it took them more than three hours to lug out their booty: thousands of bottles of Scotch whisky, beer and French wine.

The robbers came prepared: Police and witnesses said they brought three cars and a small truck to plunder Hyon Ki Yong’s trove of alcoholic drinks, which was worth more than $150,000 on the black market in a country where it is illegal for Muslims to consume alcohol.

The police, who recovered much of the stash soon after the Oct. 3 burglary, say that the three robbers were police officers and have issued arrest warrants for them and for a member of a well-known bootlegging family. They have also arrested Hyon’s housekeeper.

Senior police and customs officials say the discovery of such a large amount of liquor has led them to conclude that some North Korean diplomats are involved in selling alcohol either to make money for themselves or to provide funds for the cash-starved regime in Pyongyang.

The North Korean government is facing increasingly tough United Nations-backed economic sanctions because of its nuclear weapons and missile development programs.

“This North Korean was involved in liquor selling,” said a senior police official in Islamabad who is familiar with the investigation, in reference to Hyon.

The officer said North Korean diplomats in Pakistan have been doing this for years, though he did not provide direct evidence of such sales.

Reuters could not independently verify that Hyon had been selling alcohol.

A diplomat from the North Korean Embassy declined to comment on Hyon’s case, or the wider allegations about alcohol sales.

“It has been discussed between the embassy and MoFA (Pakistan’s Ministry of Foreign Affairs),” said the diplomat, who put the phone down before identifying himself. He did not respond to subsequent calls.

Reuters was unable to reach Hyon for comment.

Ishtiaq Hussain, the investigating police officer, said that the housekeeper, Boota Masih, had “confessed” to his role in the crime and had provided all the details.

Masih is in custody and he could not be reached for comment. It was not possible to determine if he has a lawyer.

Malik Asif, one of the officers being sought by police, denied being involved in the burglary when he was contacted by telephone. He said he is currently in hiding.

He said he has no doubts that North Koreans are involved in the alcohol smuggling business.

“They have been doing this business for a long time,” he added.

Some foreign diplomats in Islamabad have long held suspicions that North Korean diplomats in Pakistan are involved in bootlegging.

They say they believe Pakistan has turned a blind eye to bootlegging by North Koreans, perhaps out of courtesy to the historic ties between the two countries. Abdul Qadeer Khan, the Pakistani scientist lionized as the father of Pakistan’s atomic bomb, in 2004 said he had sold nuclear secrets to North Korea.

Pakistan denies being lax in policing such behavior by North Korean diplomats. “No such activity has ever been, or shall ever be tolerated,” Foreign Ministry spokesman Mohammad Faisal said.

When asked about this particular case, Faisal said: “Pakistan is actively investigating the case and any indiscretion, if proven, will be punished as per national and international laws.”

Pakistan has also always denied helping North Korea with its nuclear program.

This summer, the U.S. Embassy in Islamabad along with South Korean and Japanese counterparts, lodged a complaint with the Ministry of Foreign Affairs about the size of the North Korean mission in Pakistan, because they wanted to reduce its ability to raise funds for Pyongyang by reselling imported alcohol, according to diplomatic sources in Islamabad and Seoul.

The Japanese and South Koreans had been making such requests for more than a year, according to a source in Seoul. A Japanese Foreign Ministry source has denied knowledge of the demarche.

The source in Seoul estimates North Korea has 12-14 diplomats in Pakistan, split between Islamabad and Karachi, prompting some diplomats to wonder why Pyongyang needs so many representatives when — according to Pakistan central bank data — official trading with Pakistan has not been carried out since August 2016.

Washington has been tightening the diplomatic and economic noose around North Korea, seeking to cut its foreign sources of funding amid fears the world’s most isolated regime is on the cusp of developing intercontinental ballistic missiles capable of carrying nuclear warheads to American shores.

The U.S. Embassy in Pakistan declined to comment, as did the Foreign Ministry in Tokyo. The South Korean Foreign Ministry said: “Our government is closely monitoring any movement concerning illegal activities of North Korea but we cannot officially confirm this case.”

Pakistan’s Foreign Ministry didn’t respond to questions about the pressure it faced from other nations over the size of North Korea’s mission.

When Hyon discovered the robbery on Oct. 4 after returning to Islamabad from a trip to China, the diplomat rushed to the nearby police station to report the crime.

“He was angry and upset,” said Hussain, the police officer who interviewed Hyon in Islamabad’s Kohsar police station. “And very worried.”

Hyon told the police the robbers had fled with 1,200 bottles of Johnnie Walker Black Label whisky, 200 cases of wine, 60 cartons of beer, dozens of bottles of tequila, two diamonds and $3,000 in cash, according to a police document. On the black market, the whisky alone is worth $80 per bottle, or a total of $96,000.

Hyon and the North Korean Embassy told police the alcohol was imported legally and presented documents to back up its case. Police declined to make the documents available.

A week after the robbery, North Korea’s ambassador to Pakistan met the Foreign Ministry’s chief of protocol and requested Hyon’s missing items be returned, according to a ministry document seen by Reuters.

It is unclear whether Hyon, who would have diplomatic immunity, is himself under investigation.

Documents reviewed showing four separate alcohol import orders by the North Korean Embassy between March-December 2016 paint a picture of a mission importing alcoholic drinks that would be far above any reasonable personal needs of its diplomats.

During the nine-month period, the embassy imported 10,542 bottles of French Bordeaux wine through Truebell, a United Arab Emirates-based company. The four orders, billed by Truebell at $72,867, also included a total of 17,322 cans of Heineken and Carlsberg beer, as well as 646 bottles of Champagne.

A person who answered the phone on Truebell’s Sharjah, UAE number said the company no longer has any dealing with North Korea, but did not elaborate, and would not answer any more questions.

Alcohol is a sensitive issue in Pakistan.

Muslims, by law, are not allowed to consume alcohol but many among the Westernized elite drink.

Non-Muslims such as Christians, Hindus and Sikhs, accounting for about 3 percent of the population between them, are allowed to drink alcohol but obtaining high-quality imported liquor and wine is almost impossible through legal means.

This has spawned a lucrative black market. Alcohol is smuggled across borders and through sea ports, while several diplomats from poorer countries said they had been offered thousands of dollars by bootleggers to buy their quarterly “alcohol quotas.”

“I’ve been approached five times, usually at diplomatic receptions,” said one non-Western diplomat.

Under Pakistan’s rules, Hyon, who has the first secretary rank at the North Korean Embassy, would every three months be allowed to import a consignment of alcohol. Under one of the allowed formulas that would mean 120 liters of various spirits, 18 liters of wine and 240 liters of beer — only a fraction of the amount he reported missing.