People granted asylum in the UK will have to wait 20 years before they can apply to settle permanently, under plans due to be announced by Home Secretary Shabana Mahmood on Monday.

The major shake-up to asylum policy comes as the government seeks to reduce small boat crossings and asylum claims.

Under the plans, people who are granted asylum will only be allowed to stay in the country temporarily, with their refugee status regularly reviewed and those whose home countries are then deemed safe told to return.

Currently refugee status lasts for five years, after which people can apply for indefinite leave to remain.

Now the home secretary wants to cut the initial period from five years to two-and-a-half years, after which refugee status will be regularly reviewed.

But she plans to significantly lengthen the time it will take to gain permanent residence in the UK from five years to 20.

Mahmood told the Sunday Times the reforms were "designed to essentially say to people: do not come to this country as an illegal migrant, do not get on a boat".

She continued: "Illegal migration is tearing our country apart", adding that it was the government's job to "unite our country".

"If we don't sort this out, I think our country becomes much more divided," she told the newspaper.

The policy has been copied from Denmark, where a government led by the centre-left Social Democrats has presided over one of the toughest asylum and immigration systems in Europe.

In Denmark, refugees are given temporary residence permits, typically of two years, and in effect have to re-apply for asylum when they expire.

And Mahmood's new approach will certainly face opposition from some Labour MPs.

Liberal Democrat home affairs spokesperson Max Wilkinson said it was "right the government looks at new ways to fix the disorderly asylum system created by the Conservatives".

He added that Labour "shouldn't kid itself that these measures are an alternative to processing claims quickly so we can remove those with no right to be here".

Enver Solomon, chief executive at the Refugee Council, described the government's plans as "harsh and unnecessary", and said they "won't deter people who have been persecuted, tortured or seen family members killed in brutal wars".