Britain stands to lose £120 million it has paid to Rwanda if the plan to deport migrants is ruled unlawful by the courts.

Officials for the east African nation’s government confirmed it has received the entire initial payment for the agreement signed in April and that the funds are already “committed”, with some money spent on preparations for arrivals.

It comes in a week where there has been a wave of critical reports about the UK’s immigration and asylum policies and operations, including the Rwanda plan.

The first deportation flight was grounded in June after a series of legal challenges, and another attempt is yet to be scheduled.

Last month, Downing Street conceded that some cash had been paid but refused to say how much or when this had happened, saying the information was “confidential”.

On Friday, Rwandan government spokeswoman Yolande Makolo said: “There was an initial transfer of £120 million. This has already been paid and we are already using the funds to prepare.”

Asked by reporters whether the money would need to be repaid to the UK should the plan be barred by the courts, Ms Makolo said: “It’s paid over, it’s committed. Part of it has been used.”

She insisted Rwanda remains “committed” to the partnership, adding: “We are determined to make it work.”

Several asylum seekers, the Public and Commercial Services union and charities Care4Calais, Detention Action and Asylum Aid are challenging the legality of the Home Office policy, with the next court hearings due in September and October.

Doris Uwicyeza Picard, chief adviser to the Rwandan justice minister, told reporters: “We are confident in the legality of this partnership.”

But she added that if judges do rule against the deal, the Rwandan government would work on “solutions to these problems”.

The ongoing court cases have raised the prospect that a flight may not be attempted again until the winter.

Some migrants issued with Rwanda removal directions have already been released from immigration detention because, as yet, another flight has not been lined up.

When asked whether the government is frustrated about the legal challenges, Ms Makolo said they were “expected”, adding: “We remain ready to receive the migrants and we are using this time to prepare and we’re confident it will go ahead.”

Pressed on if there were concerns the agreement could be shelved if the new prime minister decides it should not proceed, Ms Makolo said: “It would be a big loss to not be able to see this bigger vision come to life.”

During the briefing, the Rwandan government officials hit back at criticism of its poor human rights record.

Ms Makolo also took aim at opponents who she said were depicting Africa as a “hell-hole” and somewhere that was “poor and full of disease and no opportunities”.

Earlier this week, a High Court hearing revealed that the Foreign Office advised the UK Government against sending asylum seekers to the east African nation and the country had been accused of recruiting refugees for military conflicts.

Ms Makolo said: “It is wrong to accuse us of that sort of thing. What we do is offer people a home and safety here.

“We do not get involved in recruitments for whatever armed movements. Once the refugees are here, they’re under our care and the care of UNHCR (the UN’s refugee agency). So that is incorrect information. And we want to challenge that because it’s not true.”

Assertions from the former UK High Commissioner to Rwanda were “based on wrong information”, she added.

Ms Picard said they had already been in touch with the UK to “correct the record” on the statements made, adding: “We want to ensure the country’s asylum process is understood by the court as being on par with international standards of asylum processing and refugee protection”.

Ms Makolo expressed “surprise” at critical comments from the UNHCR about the scheme, saying they had never raised concerns with the government directly.

“We’ve had a very good working relationship with the UNHCR for decades,” she added, while Ms Picard said the agency’s comments were “based on limited understanding of our asylum process”.