Twenty migrants deported from the United States have arrived in Liberia, the first group of up to 1,200 people the West African country says it will receive under a new agreement.

The arrangement has drawn concern from immigration lawyers over the rights of deportees sent to countries they do not call home.

The 20 migrants landed at Roberts International Airport outside Monrovia on Thursday, marking the start of a programme that could see as many as 1,200 people transferred to Liberia from the United States.

Liberian authorities say the deportees may include nationals from Africa as well as people from North and South America and the Caribbean.

The agreement is part of a broader US immigration policy under President Donald Trump that has involved sending deportees to third countries rather than directly to their countries of origin.