A delegation led by Boston's Cardinal Sean O'Malley arrived in Cuba on Monday, where they will meet with church leaders.

They will also look over reconstruction work to repair damage caused by three hurricanes last year, said Father Andrew Small, director of the U.S. Conference of Catholic Bishops' Collection for the Church in Latin America.

But the main purpose of their five-day trip is to send a message to the White House that it must move more quickly to improve U.S.-Cuba relations.

"Isolation doesn't help change. There has to be greater contact. And the Obama administration has been, unfortunately, encouraging but painfully slow," Small said.

"We need some radical changes, particularly from the U.S. perspective," he told Reuters in the courtyard of a Havana church.

Cuba and the United States have been at odds since the 1959 revolution that put Fidel Castro in power and eventually turned the island just 90 miles off the Florida coast into a communist state.

The political atmosphere has warmed under Obama, who has said he wants to "recast" U.S.-Cuban relations. He has taken small steps in that direction by slightly easing the 47-year-old U.S. trade embargo against the island.

But he has said further changes will depend on Cuba releasing political prisoners and making progress on human rights.

Cuba has said it is willing to discuss all issues, but that it will not make unilateral concessions to the U.S.

'UNFREEZE RELATIONSHIPS'

The U.S. Catholic bishops support ending the embargo, imposed since 1962 to undermine Cuba's communist government, and also the lifting of a travel ban on Americans wanting to visit the island, Small said.

"We are here very much showing our care and concern (to the Cuban Church). But we will be taking those messages back to those who in some sense are preventing greater openness and greater dialogue," Small said.

"I think to the extent that we can be a bridge between those who historically have not been able to talk to each other, we can unfreeze some of those relationships," he said.

Many Cubans are nominally Catholic in a country where relations between church and state have been tense for years, but have improved in the last decade.

The U.S. Conference of Catholic Bishops donated $850,000 for the rebuilding of churches and parishes damaged by hurricanes Gustav, Ike and Paloma in 2008.

The U.S. delegation includes bishop Thomas Wenski of Orlando, Florida and auxiliary bishop Oscar Cantu of San Antonio, Texas.

Their trip follows an unpublicized visit in June by Timothy Broglio, archbishop for the U.S. military, who went to the U.S. naval base in Guantanamo, then met with church leaders in several Cuban cities.