London(CNN) Britain's home secretary is facing criticism after issuing a formal apology to just 18 members of the so-called Windrush generation who the government believes could have been wrongfully detained or removed from the UK.
In a statement released Tuesday by the UK Home Office, Sajid Javid said that the 18 people had been identified during a review of almost 12,000 cases of detention and removal that began after the scandal regarding the treatment of so-called Windrush immigrants -- a group of Commonwealth citizens who arrived in Britain more than five decades ago and who have the right to stay -- erupted earlier this year.
Called the Windrush generation because the first of their numbers came to the UK on the Empire Windrush passenger liner in 1948, they were the first large group of Caribbean migrants to arrive in the country.
Of the 18 cases identified, 11 left the country voluntarily, while seven others were detained and subsequently released without being removed, according to the statement. Those who are not in the UK will be given the option to return.
"The experiences faced by some members of the Windrush generation are completely unacceptable and I am committed to righting the wrongs of the past," Javid said.
The statement sparked an immediate backlash, with Amnesty International UK describing the "narrow" apology to just 18 individuals as "worrying" and calling for the government to "urgently change tack."
Javid's apology "brings into question whether the Home Office has a realistic grasp on all the people it has wrongly detained and removed following the exposure of its appalling treatment of the Windrush generation," said Steve Valdez-Symonds, Amnesty International UK's Refugee and Migrant Rights Programme Director.
Labour MP David Lammy, who has led parliamentary opposition to the government on this issue, described the apology as "a drop in the ocean & just spin until we know full numbers deported."
The critique was driven partly by the government's acknowledgment that a further 146 people had been identified -- in addition to the 18 -- who may also have been wrongfully detained or removed. Those Windrush citizens were not included in Javid's apology, however.
Home Affairs Select Committee Chair Yvette Cooper welcomed the move by the Home Office but said that "many more people ... have been affected and need contact, support and a similar apology now."
Both Lammy and Cooper also called for quicker action to compensate victims. The Home Office confirmed in Tuesday's statement that a compensation plan would be established, but no time frame was given.
READ MORE: Invited to the UK decades ago, now they must prove they're British
The scandal was exposed earlier this year after a raft of cases were reported where individuals who had arrived in the UK from Commonwealth countries before 1973 were struggling to prove their citizenship status under tough new immigration laws. Many were alleged to have been refused medical care, denied housing and threatened with deportation.
In April, Prime Minister Theresa May apologized for her government's treatment of this group of Caribbean migrants, insisting they were still welcome in the country.
Then Home Secretary Amber Rudd -- who claimed she had no knowledge of any Windrush citizens wrongfully removed -- was forced to resign in the midst of the furore
The Windrush issue is one of several currently plaguing the Home Office, which has been accused of subjecting legal migrants to its "hostile environment" policy, which was designed to target people in the country illegally.
Several cases have emerged recently of Afghan interpreters who served with the British military being wrongly deported or threatened with removal, while the Home Office is also facing accusations of wrongdoing after deporting more than 4,600 foreign students who it accused of cheating on English language tests.
In a statement in July, provoked by the Windrush debate, the Home Affairs Committee called for a "root and branch reform to the Home Office's culture, policy and approach to immigration."