Image caption Dewa is alleged to have been propositioned by the judge at least 15 times

A senior judge in Afghanistan has been secretly recorded demanding money and marriage from a young woman seeking his help in her divorce case.

In the recording the judge can be heard asking for over $2,000 as well as the woman's hand in return for his help.

The judge has strenuously denied the allegations, arguing that he was only "joking" about the marriage proposal.

Correspondents say the case highlights widespread corruption in the Afghan justice system.

The head of Afghanistan's anti-corruption department, Azizullah Ludin, has promised to take action.

"Once we get the evidence, we will investigate this case jointly with the Supreme Court and I will personally involve the chief justice," he told the BBC.

President Karzai, who has repeatedly promised to do more to tackle corruption, has also ordered officials to look into the case.

His spokesman said he had read the BBC story with "great interest" and asked for "a serious investigation".

'Cover you in gold'

The woman seeking the divorce, Dewa, told the BBC that when she attended court in the eastern city of Jalalabad the judge, called Zahorudin, offered to visit her family home to help with the case. Once there he demanded money.

As a radio journalist, Dewa had access to recording equipment which she hid under her robe.

"When the talk turned to paying bribes... I got my recorder and started to record his voice."

The BBC Afghan Service has obtained a copy and verified the recording.

In it the 65-year-old judge can be heard asking for 20,000 Afghanis ($390; £240) for himself and another 100,000 Afghanis ($1,960; £1,215) for the judge presiding over the divorce case.

When Dewa refused the proposal and said she was unable and unwilling to pay, Zahorudin made a different offer, she alleges.

On the recording he can be heard promising to resolve Dewa's financial problems if she agrees to marry him.

"I will pay two million [Afghanis] for you and cover you in gold from your toes to your forehead," he is heard saying.

Dewa's mother was present during the conversation and said that she could not hide her astonishment.

"I was very sad," she said, "telling myself that this man has sons, daughters-in-law and a wife. But this dirty man is now trying to take advantage of our desperate situation," she told the BBC.

When the BBC contacted the judge by telephone, he at first claimed that he did not know Dewa. When confronted with the evidence, he claimed the journalist had cut and pasted his voice using her radio editing skills.

He said that the entire story was a "conspiracy by rival judges and provincial elders" to prevent him from getting a higher ranking position.

As for his marriage proposal Zahorudin claimed he had been talking in jest. "She was saying 'no-one will marry me', so I offered to marry her. I told her this jokingly."

But in the 15-minute recording Zahorudin repeated his proposal of marriage 15 times.

He also boasted how his standing could protect Dewa.

"A court cannot end animosity. But when you marry a strong man, he will put an end to animosity," the judge is heard saying.

"He will say to your current husband... From now on I don't want to see your face, if you do show your face, I will shoot you in the head."

Dewa's family took the tape to the Supreme Court in Kabul, but so far no action has been taken against the judge.

The divorce case itself has remained unresolved.