30 angry protesters from No Borders, Stop Deportation and other groups are blocking the joint entrance to the two detention centres near Heathrow airport. Six of them have encased their arms in glass and plastic tubes attached to concrete barrels, while others are holding banners and shouting slogans against the 'brutal deportation machine.'

Three coaches carrying over 30 of the deportees to the airport have not been able to leave the complex. Another 30 are supposed to be taken at the same time from Brook House detention centre at Gatwick airport and Campsfield House in Oxfordshire. In total, it is expected that the flight, scheduled to leave an undisclosed airport at 11pm today, will carry between 60 and 70 deportees, accompanied by twice as many private security guards and immigration officers.

One of the protesters, who preferred to stay anonymous, said: "Mass deportation flights have become the government's favoured way to deport those who have fallen foul of its inhumane immigration controls. They're meant to save money and keep deportations outside the public gaze. But while every deportation is a violation of people's right to freedom of movement, these charter flights are a particularly sordid way to do that. On top of the trauma and hardship caused by deportation, these flights further undermine the legal rights of the refugees and asylum seekers."

Campaigners claim that many of the deportees have not exhausted all legal avenues available to them and have not had access to adequate legal representation. The emphasis of mass deportations, they argue, is on filling the flight and "getting rid of as many, as soon as possible." Solicitors acting on behalf of the deportees had sought a judicial review in the High Court as to whether the flight as a whole is legal.

Earlier this month, some of the detainees held in Campsfield went on hunger strike in protest at their planned deportation. In a statement they said: "Some of us don't have any homes or nowhere to go in Iraq. If we were returned we would be left to survive for ourselves on the streets with nothing. Some of us don't even know if our family members are alive or dead because we haven't had any contact with them for a long time... We have family and friends here. Being parted from them at this time is very hard and stressful for both sides... Everyone has the right to be able to live in a safe country."

According to media reports and evidence collected by the International Federation of Iraqi Refugees (IFIR), many of those who have been deported to Iraq over the past few years are now living in hiding, in fear of the persecution they originally left Iraq to flee. Some have been assassinated or kidnapped and killed, while others have had mental breakdowns or committed suicide days after being deported. Many more have had to leave the country and become refugees again.

IFIR's secretary Dashty Jamal said: "The UK government is responsible for the tragedy in Iraq. They are playing politics with the lives of Iraqi refugees. They are making a deal with the despotic Iraqi regime, which the Iraqi people are currently rising up against, to send people back."

This is not the first time that Colnbrook and Harmodsworth have been blockaded by anti-deportation campaigners. In May 2009, a similar blockade to try and stop a mass deportation flight to Iraqi Kurdistan ended with six of the activists being violently arrested, only to be found not guilty by a magistrates judge.