LONDON (Reuters) - British Prime Minister Keir Starmer's government will retain a ban on asylum seekers being able to claim protections under modern slavery and other human rights laws, even as its ministers have previously criticised those measures.

Starmer is under pressure to deal with tens of thousands of people who arrive to the UK each year on small boats, a key issue of concern for British voters, after he pledged in last year's election campaign to "smash the gangs" controlling the people smuggling trade.

The Border Security, Asylum and Immigration Bill introduced to parliament on Thursday will allow the police to seize the mobile phones of asylum seekers to help track down people smugglers, and target those suspected of supplying parts used in the small boats to transport people to England.

The Labour Party, which won power in July, also plans to retain parts of legislation passed by the previous Conservative government that will disqualify asylum seekers using modern slavery laws to challenge decisions to remove them, and the power to detain child asylum seekers for up to 28 days.

Labour had voted against those measures in parliament when legislation on them was passed in 2023.

Starmer said at the time that the decision to deny asylum seekers using modern slavery laws would "drive a coach and horses" through protections for women trafficked to Britain.

Jess Phillips, now a junior interior minister, said in 2023 the legislation was a "traffickers' dream" because it would hide victims of modern slavery.

Starmer's office and the interior ministry did not immediately respond to a request for comment.

Immigration and asylum is the second most important issue to voters after the economy, ahead of health, according to a tracker poll published by YouGov.

Government figures show that 36,816 people came to Britain via small boats last year, a 25% jump from the 29,437 who arrived in 2023.

The latest government statistics on Channel crossings make 2024 the second-highest year for arrivals since data was first collated in 2018.

Concern over immigration was a leading factor in Britain's decision to vote to leave the European Union in 2016, but successive governments have failed to reduce both legal and illegal migration.

(Reporting by Andrew MacAskill; Editing by Bernadette Baum)