What happens to asylum seekers who are sent home? As part of a BBC World Service investigation, Jenny Cuffe has followed the footsteps of failed asylum seekers sent back from Europe to the Democratic Republic of Congo. What she found raised questions over how European governments are treating those they deport.

The woman at the rear of the Air France flight to Kinshasa was still screaming as we taxied down the runway at Paris Charles de Gaulle Airport.

Hemmed in by French police officers, she pleaded to be allowed off the aircraft. As the plane took off, her screaming subsided to a low whimpering. This was a failed asylum seeker being sent back forcibly to her country of origin, the DR Congo.

Throughout the European Union, there are hundreds of people in a similar situation - nervously waiting a one-way ticket back to the Congolese capital, Kinshasa.

Although Africa's bloodiest conflict has cost an estimated four million lives since 1998, many EU countries judge it safe to send failed asylum seekers back. They say that there is a transitional government which plans elections next year.

Many asylum seekers, however, claim they will not be safe on return. I wanted to find out the truth.

Secret service

In a curtained room in down-town Kinshasa, I was introduced to "Simon", a member of the ANR, the Congolese secret service.

Based at the airport, his job includes seeking out, interrogating and, if necessary, detain returning asylum seekers.

Simon told me that returnees are taken to an office for questioning. Some are asked for a bribe of about $120.

But those who "have problems with the government" are detained. "Political dissidents, people who leave the country and go to say bad things about the government," said Simon. "We have to arrest them and show them what they did was not good."

Simon said that another task was to identity any asylum seekers with connections to DR Congo's enemies, especially Rwanda.

Simon has instructions to pick out those who have a Rwandan name, or even those who look Rwandan.

I asked him what happens to these men and women. He became evasive. They are handed over to the authorities. What happens next? He shrugged. "Everything. I cannot say more. Everything."

European informants

Simon's job relies on information coming back to Kinshasa from DR Congo's embassies in Europe. Dutch authorities are currently investigating whether dossiers which include allegations by Congolese asylum seekers have been passed to Kinshasa.

Crucially, Simon's testimony raises questions about the checks made by European authorities.

In a letter last year, the British Ambassador to Kinshasa wrote: "All passengers arriving at Kinshasa are liable to be questioned by DR Congo immigration officials. We have no evidence that returned failed asylum seekers are singled out for adverse treatment." Other European countries take the same view.

'Pierre' was deported from Brussels in April. He had sought asylum and says the scars on his arms are proof that soldiers beat him, having accused him of hiding weapons to use against the President.

The softly-spoken graduate told the BBC that on his return he was interrogated for 48 hours, whipped and taken in a jeep to Kinshasa's state prison, Makala. There, he said, the beatings continued.

The United Nations has described the regime in DR Congo's prisons as one of rape and torture. If prisoners do not have relatives to bring them food, they may eventually die of starvation, it reports.

Pierre says he was able to get out of the jail because a relative raised $900 to buy his release. But he remains in hiding after the guards said they knew where to find him.

Human rights lawyer Celestin Nikiana has started to list the prisoners in Makala. He has found two of the prisoners to be former asylum seekers who have been there for more than five years without charge: Alain Londole , who was returned by Belgium, and Willy Ayi-Ansha, sent back by Italy. Mr Nikiana believes there is at least one other asylum seeker, returned from Belgium, being kept in the prison's political wing.

Secret jails

The UN has also criticised unofficial jails run by DR Congo's national intelligence service. These are said to be places where prisoners are subjected to "cruel, inhumane or degrading treatment and even torture". Human rights campaigners say they have information that one former asylum seeker is being kept in one of these secret centres.

Azaris Ruberwa, vice-president in charge of defence and security, denies returning asylum-seekers are unwelcome.

But he added: "There are still some secret services or security services which commit some abuses against the laws of the country. We hope that once the election is organised these problems will all be solved.

"I don't deny the fact that there are cases of security agents who are abusing, but I can guarantee that there is no policy from the government here to do any harm to detainees."

Although campaigners have warned some people deported from Europe may be put at risk, they have not yet been able to produce convincing evidence.

Government checks

Under the present arrangements, the legal responsibility to check that returned asylum seekers will be safe rests with individual European governments.

And despite plans currently being developed for a common European policy on migration and asylum, there at present no plans to make the European Commission responsible for monitoring what happens when the asylum seekers are sent back.

This means that governments like the UK take on trust the good intentions of receiving countries.

For its part, however, the Home Office said those who are returned to their home countries are only sent back because it has been "judged safe" for the deportation to take place.

"To date, we have not received any objective evidence to support allegations of either systematic or arbitrary detention or ill treatment of returnees," said a spokesman.

"The situation in Democratic Republic of Congo, including the treatment of returnees, is kept under review in consultation with the United Nations High Commissioner for Refugees and other EU countries.

"We do not routinely monitor the treatment of returnees to any country. We would not remove them if we considered that they were likely to suffer persecution on their return.

"The only people who are removed are those who do not have a well-founded fear of persecution and do not therefore need international protection".