Eight more members of the Windrush generation who may have been wrongly deported by UK authorities have been found to have died, taking the total to at least 11, the home secretary has confirmed.

Sajid Javid said British officials had also been unable to contact many of those thought to have been caught up in the scandal, suggesting the true death toll could be higher still.

The shadow home secretary, Diane Abbott, called the latest revelations a “complete disgrace”. She demanded justice for those affected and an end to the hostile environment policy championed by the prime minister, Theresa May, during her six-year stint as home secretary.

“Deaths of deported British citizens and deportations for convictions that never existed all point to the real evils of the hostile environment,” she said.

“These piecemeal updates show that the government is simply not taking this seriously enough.

“We still do not know the true scale of this scandal, like how many people were deported and imprisoned. The government refuses to implement a hardship fund, even though it’s clear the compensation scheme will not be available for many months.

“The Windrush generation must have justice and the hostile environment must end.”

Javid provided the figures in a monthly update to the home affairs select committee, chaired by Abbott’s colleague, Yvette Cooper. He said there were 83 cases in which it had been confirmed people were wrongfully removed from the country and officials fear there may be a further 81.

In the former cases, the Home Office has made contact with 42 of the affected people, while a further 33 of them have proven uncontactable – eight of whom were found to have died.

Of the 81 people whose cases the Home Office sees as being less clear-cut, officials have contacted 75, leaving six yet to be reached – three of whom are believed to have died. In August, officials had said they had identified only three cases in which someone had died.

The overall numbers of those affected could be revised up after the Home Office said it would stop excluding people who were accused of minor offences, but then either not prosecuted or acquitted.

The government department has, so far, excluded any cases which have a “criminal case type” marker. Javid said this approach has been reviewed “to ensure we have not adopted too broad a definition”.

In his letter, Javid told MPs: “I continue to believe it is important that we take a cross party-approach which recognises the most important thing we can do is ensure the wrongs which some members of the Windrush generation have faced are put right. I can reassure members that my department remains entirely focussed on righting the wrongs experienced by the Windrush generation.”