Israel’s proposal to expel thousands of migrants originating from Africa appeared to hit a roadblock when it emerged prisons lack the capacity to incarcerate those who refuse to leave.

The controversial plan to offer $3,500 (£2,588) in cash to each of the estimated 35,000 African migrants in return for voluntarily leaving the country was approved by the cabinet last week.

Those who take the deal would be sent to Rwanda, irrespective of whether it is their home country, while anyone who refuses will face an indefinite jail term.

Rwanda will reportedly receive $5,000 (£3,700) for each migrant it accepts.

But with thousands expected to turn the offer down, it has emerged that the government did not consider capacity in Israel’s overcrowded prisons.

“The plan was formulated without coordination with us and there is no way we could handle the thousands of indefinite arrests it will entail,” a prison service source said on Wednesday.

There are two centres for African migrants in the Negev desert — Saharonim, classified as a prison facility, and Holot, an “open” facility.

Prime Minister Benjamin Netanyahu instructed the National Security Council to examine the option of “forcible deportations”, but it is legally problematic to force a person to board a plane against their will.

Refugee rights organisations say there are no clear assurances that the deportees will be adequately treated once they land in Rwanda, despite statements from the country’s government.

They also claim that Israel has effectively ignored the requests for political asylum by over 14,000 of the migrants, who are overwhelmingly from Eritrea and Sudan.

“There hasn’t been an honest effort to comply with the terms of the international convention on the status of the refugees, which Israel was not only one of the first countries to sign [but] played a major role in drafting,” said Jean-Marc Liling, executive director of the Center for International Migration and Integration.

He accused the government of having only cursorily examined a fraction of the asylum requests, granting just ten of the four thousand requests that were considered.

Over 50,000 African migrants arrived in Israel until 2012, when a new border fence with Egypt cut off smuggling routes from Sinai.

Mr Netanyahu has made their deportation a personal crusade in recent months. The policy is popular with his base.

He made two visits last year to the south Tel Aviv neighbourhoods where most of the migrants live, in a show of solidarity with working-class residents who complained about conditions since the migrants arrived.

“The infiltrators can cooperate and leave in a respectable and humane way or we will use other methods,” he told Wednesday’s cabinet meeting.

“What we are doing is totally legal and necessary.”