Boris Johnson said 50 people have been told they will be sent to Rwanda within the next fortnight, and that he was ready to fight with “leftie lawyers” seeking to challenge the government’s plans for refugees.

Under the £120m scheme announced last month, people deemed to have entered the UK unlawfully will be transported to the east African country, where they will be allowed to apply for the right to settle.

The plans have faced widespread criticism from human rights charities and even some Tory backbenchers, including the former prime minister Theresa May, as well as the archbishop of Canterbury, Justin Welby.

However, in an interview with the Daily Mail, Johnson remained defiant, stating that the first 50 “illegal entrants into this country” have already been served notice that they will be sent to the African country within a fortnight.

“There’s going to be a lot of legal opposition from the types of firms that, for a long time, have been taking taxpayers’ money to mount these sorts of cases, and to thwart the will of the people, the will of parliament. We’re ready for that,” he said.

“We will dig in for the fight and, you know, we will make it work. We’ve got a huge flowchart of things we have to do to deal with it, with the leftie lawyers.”

When asked if he may respond with a review of the European convention on human rights, Johnson said: “We’ll look at everything. Nothing is off the table.”

The Home Office published its own equality impact assessment for the policy this week, and said there were “concerns” over the treatment of some LGBTQI+ people in the east African country. It said investigations pointed to “ill treatment” of this group being “more than one-off”.

Tom Pursglove, the minister for justice and tackling illegal immigration, said decisions to transport asylum seekers to Rwanda would be considered on a “case-by-case basis” and did not deny that people fleeing war in Ukraine could be among them.

Pursglove said: “There is absolutely no reason why any Ukrainian should be getting in a small boat, paying a smuggler to get to the UK.”

He was also unable to point to any calculations that the government’s Rwanda relocation policy would reduce the number of people arriving in the UK by small boats.

“This is a new and untested policy at this point in time,” he said. “I do think that, in the fullness of time, we will see this policy, as part of a wider package that we are introducing, really shift the dynamic.”

When challenged on human rights concerns surrounding the policy during a home affairs select committee hearing, Pursglove said that “overall, Rwanda is a safe and secure country” to use for resettlement. He argued there were “no systematic breaches” of human rights obligations in the country.

After the announcement of the government’s relocation scheme, more than 160 charities and campaign groups called on the prime minister to scrap what they described as “shamefully cruel” plans.

The archbishop of Canterbury used his Easter sermon to question the move, saying there were “serious ethical questions about sending asylum seekers overseas”.

May, herself a former home secretary, said she did not support the idea “on the grounds of legality, practicality and efficacy”.