The general made an elementary mistake. Told by his superiors that his new posting as chief of police in a drug-rich northern province would cost him “one hundred and fifty thousand”, he assumed the bribe to be in Afghan currency.

He paid the money to a go-between at a rendezvous in Kabul’s Najib Zarab carpet market. For two days he was lorded in the office of General Azzam, then Chief of Staff to the Interior Minister, helping himself to chocolate and biscuits. “I must have eaten a pound of the stuff,” he recalled.

But on the third day he received a different welcome. “Get this mother****** out of my office,” Azzam screamed, said the general. Hustled outside, he quickly discovered his error. He should have paid $150,000 (£73,000) rather than a paltry 150,000 Afghanis for the bung.

Now living in disgruntled internal exile in northern Afghanistan, his verdict on his former employers is succinct.

“Everyone in the Ministry of Interior is corrupt,” he told The Times. “They wouldn’t sleep with their wives without wanting a backhander first.”

He never, though, expressed surprise. Governmental corruption in Afghanistan has become endemic and bribes to secure police and administrative positions along provincial drug routes is an established procedure.

“The British public would be up in arms if they knew that the district appointments in the south for which British soldiers are dying are there just to protect drug routes,” said one analyst. Western and Afghan officials are also alarmed at how narco-kleptocracy has extended its grip around President Karzai, a figure regarded by some as increasingly isolated by a cadre of corrupt officials.

“The people around him tell him of a cuckoo land,” said Shukria Barakzai, a Pashtun MP who is both a friend and critic of Karzai. “He circles within a small mafia ring who are supporting the destruction of the system. At the beginning there were only 10 to 15 of them but since then they have spread like a cancer in Afghanistan.”

The Ministry of Interior, key to establishing security in the country, remains the worst offender. Disaffected police officers have named, to The Times, General Azzam, recently appointed Chief of Operations after his stint as Chief of Staff, and his deputy General Reshad as the prime recipients of bribes.

The lawmen say they categorise Afghanistan’s 34 provinces as A, B or C states. ‘A’ denotes those with the highest potential profits for drug-running; ‘C’ states are the least remunerative. The bribes to buy a position in an A-grade province can be vast, up to $300,000. The rewards are even bigger. One border police commander in eastern Afghanistan was estimated by counter-narcotic officials to take home $400,000 a month from heroin smuggling.

This summer a border police vehicle was stopped outside Kabul and found to have 123.5kg of heroin, with a value of nearly $300,000, bagged in the back. The five men inside, an officer, three policemen and a secretary, were under the command of Haji Zahir, formerly Border Police commander of Nangarhar province. Haji Zahir was questioned and removed from his post. He was never charged.

Even the lowlier posts in provinces free of poppy traffic have a price. “To buy a position as a detective in any province you pay $10,000,” explained one police colonel, now on indefinite leave because he refused to pay a bribe. “Then you pay your superior a cut of the money you make through bribes or trafficking.”

One former governor told The Times that every judge in his province had been corrupt. He claimed there were cases of the police handing detainees to the Taleban, or helping to transport Taleban commanders from one province to another.

“The Government has essentially collapsed,” he said. “It has lost its meaning in the provinces, it has lost the security situation and lost its grip on civil servants. Corruption is playing havoc with the country.”

The international community has played its own part in contributing to the crisis. One analyst in Kabul said: “It’s not Afghan culture. It’s a culture of impunity. We created it. We came in in 2001 with cases of cash and made certain people untouchables.”

The dozens of drug-funded villas — “narcotechture” in expat parlance — that have sprung up around foreign embassies in Kabul’s Sherpur district are a testament to the untouchable status of former warlords.

Corruption among police and local authorities is worst in southern Afghanistan, where drug profits are highest. Despite his repeated public denials, President Karzai’s half-brother Wali, head of Kandahar’s provincial council, continues to be accused by senior government sources, as well as foreign analysts and officials, as having a key role in orchestrating the movement of heroin from Kandahar eastward through Helmand and out across the Iranian border.

Britain has been keen for Kabul to begin arresting top drug smugglers in its ranks. Yet diplomats fear the country’s judicial system is so weak that the men would quickly be released or escape. Meanwhile, America has been lacklustre in lobbying for high-level arrests, fearing such detentions would further destabilise matters.

The Afghan Government fears that if corrupt officials in the south were replaced by staunch law enforcers, the huge profits from heroin trafficking would end up with the Taleban.

Kabul has, though, made efforts. A new agency, the directorate of local government (IDLG), was supposed to give the President rather than the Ministry of Interior more say over the appointment of provincial governors, a system notorious for its corrupt procedures. However, many of the IDLG staff were simply transferred from the Interior Ministry, tainting its potential from the start. Afghan anti-corruption agencies similarly lack cohesion and clout. Izzatullah Wasifi, director of Afghanistan’s GIAAC anti-corrution force, said he had been unable to brief President Karzai even once during the past 11 months.

His own force is already under suspicion from rival anti-corruption players in the offices of the Attorney-General and the Ministry of Finance, who in turn face allegations of embezzlement and bribery. Wasifi did time in an American penitentiary 20 years ago for dealing heroin. “You expect my guys to be clean working for $200 a month versus the millions in drug bribes?” he asked. “I don’t see any serious measures being taken to solve the problem.”

Times Recommends

• Times Charity Appeal: SolarAid
• Is it Black Monday all over again for Dubai?
• Behind the scenes at the biggest deal