Senior Conservative MPs have questioned the logic behind Government plans to send asylum seekers to Rwanda, as controversial immigration reforms edged closer to becoming law.

The Nationality and Borders Bill would allow the UK to send asylum seekers to a “safe third country” and to submit claims at a “designated place” determined by the Secretary of State.

But MPs and campaigners have criticised the plans to forcibly send to Rwanda thousands of asylum seekers who arrive in the UK in unauthorised Channel crossings.

A £120 million economic deal has been struck with Rwanda and cash for each removal is expected to follow.

Conservative MP Simon Hoare (North Dorset) speaking as the Commons considered Lords amendments made to the Bill, said: “A safe route clearly would kill the evil traffic of people smuggling at a stroke, that’s one way of dealing with it.

“I fail to see how moving people to Rwanda is going to in any way disrupt this money-making scheme which these people traffickers have. They’re just going to use different routes to land people on our shores. I’m just not getting it, I’m afraid.”

Conservative former minister Sir Bob Neill suggested investing the money intended for the Rwanda immigration deal into improving the UK’s system for handling claims.

The Conservative chairman of the Justice Committee said: “(Home Office minister Tom Pursglove) asks is there an alternative in relation to the Rwanda scheme, which I accept is not directly part of this legislation.

“Can I make the point that the salary of an immigration tribunal judge, first-tier tribunal judge, is £117,000. If you put on on costs, even most generously, that’s about £200,000.

“Look at the £120 million so far committed to the Rwanda scheme, there’s about 600 first-tier tribunal judges could be bought for that, or any number of hundreds of Home Office case workers, would that not be an alternative, actually to invest in the current system – that would be a constructive alternative surely?”

Mr Pursglove said he recognised the need to consider cases more quickly, adding: “But that of itself will not solve this issue and I genuinely believe that the approach that we are taking through the comprehensive plan will shift the dial, will change the dynamic and will ultimately help us to shut down these evil criminal networks.”

Conservative former minister David Davis added: “Yesterday the erstwhile Prime Minister made the point to the Home Secretary that any group you pick as protected will then become incentivised, as it were, to cross the Channel.

“So, if you say families are protected, then that will create an incentive to have families cross the Channel. How is he going to square that particular conundrum?”

Mr Pursglove replied: “I’m not going to say any more over and above that which I’ve already set out this afternoon and which the Home Secretary said yesterday.”

He added the Rwanda agreement is in “full compliance” with domestic and international law.

Shadow Home Office minister Stephen Kinnock said Labour does not support the Rwanda plan and described the Nationality and Borders Bill as “profoundly inadequate and mean-spirited”.

He told the Commons: “The clauses on offshoring, inadmissibility, differential treatment, an offence of arrival are symptomatic of a shambolic Government that has completely lost control of our asylum system to the extent that it’s now seeking to dump its problems on a developing country that’s 4,000 miles away and which has a questionable record on human rights.”

The exchanges came before the Government started to overturn changes made to the Bill by peers, which saw MPs reject three amendments which were part of efforts to ensure any move to offshore asylum claims was subject to approval of both Houses of Parliament – along with a cost breakdown.

The Lords had also sought to remove a broad provision to make it a criminal offence to knowingly arrive in the UK without permission, and ensure any move to offshore asylum claims was subject to approval of both Houses of Parliament – along with a cost breakdown.

The upper chamber also backed measures to safeguard against prosecution of people who carried out at-sea rescues, by providing a “reasonable excuse” defence, while taking steps to prevent asylum seekers being treated differently based on how they entered the UK.

In addition, peers renewed their demand that asylum seekers be allowed to work if no decision had been taken on their claim after six months, as well as enable unaccompanied child asylum seekers in Europe to join family in the UK.

But the Government successfully removed the changes from the Bill after winning 12 Commons votes.

The tightest division saw MPs vote 294 to 242, majority 52, to reject Lords amendment 7B, which was linked to allowing asylum seekers to work if no decision had been taken on their claim after six months.

The division list showed 11 Tory MPs rebelled in a bid to retain the measure.

The Bill is currently at the stage known as parliamentary ping-pong – where a piece of legislation moves between the two Houses until agreement on the wording can be reached.