A controversial barge that is set to accommodate 500 asylum seekers has arrived in Dorset.

The Bibby Stockholm departed Falmouth in Cornwall on Monday – one month behind schedule.

It was pulled by a tugboat into Portland Port on Tuesday morning.

The vessel’s arrival in Dorset – which has been opposed by the local MP and residents – came hours after the government’s Illegal Migration Bill passed the Lords.

The first asylum seekers are expected to board the Bibby Stockholm later this month.

Downing Street has defended the use of barges to house migrants – insisting it is a cheaper alternative to accommodating them in hotels.

Rishi Sunak‘s official spokesman told reporters: “I think it’s right for the public as a whole that we move away from a situation where £6m a day of taxpayers’ money is going towards housing these individuals in hotels.

“That’s not a good use of money and obviously that puts unplanned pressure on local areas as well.

“We think it is better to open specific sites designed to house immigrants that come in, done in a more planned way.

“That’s what we are seeking to do with the Bibby Stockholm and that’s what we’re seeking to do in other parts of the country – opening up sites to take the pressure off local areas and to reduce the cost.”

A Home Office spokesperson said using vessels as accommodation will be “better value” for taxpayers and “more manageable for communities than costly hotels”.

“We continue to work extremely closely with local councils and key partners to prepare for arrival of asylum seekers later this month and minimise disruption for local residents including through substantial financial support,” they added.

During debate over the Illegal Migration Bill, Home Office minister Lord Murray of Blidworth said the UK’s asylum system was “overwhelmed” by small boat arrivals.

He told peers: “With over 45,000 people making dangerous Channel crossings last year this is simply no longer sustainable.

“If people know there is no way for them to stay in the UK, they won’t risk their lives and pay criminals thousands of pounds to arrive here illegally.

“It is therefore only right that we stop the boats and break the business model of the criminal gangs exploiting vulnerable people, ultimately enabling the government to have greater capacity to provide a safe haven for those at risk of war and persecution.”

Bill could cause ‘unimaginable harm and trauma’ to children

However, health experts have said the Illegal Migration Bill risks causing “unimaginable levels of harm and trauma” to children detained.

A coalition of doctors and leading medical experts said the legislation could cause PTSD, depression and suicidal behaviour among young people.

Shadow Culture Secretary, Lucy Powell, said Labour would not repeal the Illegal Migration Bill but remains opposed to the government’s Rwanda policy.

Last week ministers were given permission to make an appeal to the Supreme Court to get the policy moving after the Court of Appeal ruled plans to send asylum seekers to the east African nation were unlawful.

Ms Powell told Sky News’ Kay Burley on Tuesday morning that the use of barges showed the government’s plans were not working.

“These barges…are a sign of failure that the backlogs continue, that we need more and more capacity in hotels, in barges and elsewhere to deal with people who are waiting for decisions, because that’s just not happening.”

Read more: New record of Channel crossings in a single day so far this year

Shadow Home Secretary Yvette Cooper branded the Illegal Migration Bill a “con”, insisting it will “only make the Tories asylum chaos worse”.

“It fails to tackle the criminal smuggler gangs and makes it easier for traffickers,” she said.

“And it cancels asylum decision making with no return agreements in place so it will just increase the asylum backlog with even more people in costly hotels.

“The asylum backlog is a record high, the number of people in hotels is still increasing, the Rwanda plan is unravelling and June boat crossings were higher than last year. Just like last year’s Tory immigration bill, this new law is set to make things worse.”

Protests over barge arrival

Protesters gathered for the arrival of the Bibby Stockholm – with some residents raising concerns about Portland Port being used to house asylum seekers.

Some held banners saying “Refugees welcome” and “No floating prisons”.

Others said “No to the barge”.

The government is also planning to use disused airfields to house asylum migrants – but faces a High Court challenge from councillors and campaigners.

Braintree District Council and a nearby resident are bringing legal action to challenge the use of Wethersfield in Essex to house up to 1,700 men.

Dozens of asylum seekers have already been moved into the site.

West Lindsey District Council is also challenging similar plans for RAF Scampton in Lincolnshire.