The hacked adverts draw attention to charter flights which allegedly deport asylum seekers with failed or ongoing claims from the UK.
People like Jimmy Mubenga have died after being forcibly restrained on the flights, and many others have been denied access to their legal rights, according to Stop Deportation activists.
The flights each cost £250,000, and it's not clear if they're legal.
'They used to take people and put them in the slave ships, to take them and go and sell them. Now, they are doing this here'
One such ad has a message from an asylum-seeker who was allegedly imprisoned in the Yarl's Wood detention centre before being deported in May 2016.
Yarl's Wood is a slave ship... There is no white person in here, we are all Indian, Chinese and African. It is racism.
I have been in England 20 years, I paid my taxes, paid my [National Insurance]. My back is hurt from lifting older people, working with disabled children. I have worked with all my heart.
A number of allegations of serious sexual assault and abuse have been made against staff at Yarl’s Wood, with a dossier chronicling decades of abuse as residents are imprisoned for months or years without trial.
'This January, some 50 UK residents will be rounded up and forcibly deported to Nigeria, in secret'
The other subvertisement shares statistics, noting that 50 UK residents will be deported to Nigeria this January. "Some have been here most of their life", and "some will leave children and partners behind."
It's been claimed the government rounds people up to fill deportation flights to particular countries, rather than considering their individual legal claims.
End Deportations member George told the Independent the situation is getting worse:
A relatively new policy means people can be deported before their legal cases have been resolved, and are prevented from winning cases because of the difficulties of fighting a legal battle from abroad.
The persistent scapegoating of migrants, culminating in post-Brexit calls to further limit free movement, means that more people are likely to be detained and more people are going to be separated from their communities and families.
If you're angered by the adverts' message, End Deportations activist Rosa has a few suggestions:
Get involved in local community struggles with groups like Movement For Justice, the Unity Centre, Leeds No Borders, and so on.
Try to stop an immigration raid when you see one, help someone get across the border in Europe, visit someone in detention: all these seemingly small acts make a difference.
indy100 contacted Transport for London, a spokesperson commented:
This is not an authorised advert. It is fly posting and therefore an act of vandalism which we take extremely seriously. We have instructed our contractor to remove any found on our network.
indy100 has contacted the Home Office for comment on the subvertisements.