Carter, left, was met at the airport by Bruno Rodriguez, Cuba's foreign minster [Reuters]

Jimmy Carter, the former US president, has begun a three-day trip to Cuba to discuss the famously strained relations between Havana and Washington.

Carter received a low-key welcome from Bruno Rodriguez, Cuba's foreign minister, on his arrival in Havana on Monday.

The trip has raised hopes that a jailed US government contractor may be freed, but the Carter Center in Atlanta said the trip was a "private, nongovernmental mission".

The center said Carter hopes to learn about Cuba's new economic policies and discuss ways to improve US-Cuba ties.

Nonetheless, Carter is expected to discuss the possible release of Alan Gross, who earlier this month was jailed for 15 years for providing illegal internet access to Cuban dissidents under a US pro-democracy programme.

Gross was convicted of "acts against the independence or territorial integrity" of Cuba, but the US government contends he only provided internet access to Jewish groups and committed no crime.

Many think Cuba may be open to freeing Gross soon because of humanitarian concerns in that Gross' 26-year-old daughter and 88-year-old mother are both suffering from cancer.

Carter last visited Cuba in 2002, in a groundbreaking trip that made him the only US president, former or sitting, to visit Cuba since a 1959 revolution brought Fidel Castro to power.

Castro stepped down as president three years ago and was succeeded by his younger brother Raul.

In his 2002 visit, Carter urged Washington to end its long trade embargo against Cuba.

He also called for democracy and better human rights in Cuba and praised the Varela Project, a pro-democracy petition calling for greater freedom of expression and amnesty for political prisoners.