The United States will urge Cuba to lift travel restrictions on US diplomats and agree to opening embassies in historic talks on restoring relations this week in Havana, a senior US state department official has said.

The talks on Wednesday and Thursday will be led by Roberta Jacobson, the top US diplomat for Latin America, in the first visit to Cuba in 38 years by a US assistant secretary of state.

"We are looking forward to the Cubans lifting travel restrictions," the official told reporters, referring to curbs that mean US diplomats are typically not allowed outside Havana. The same applies to Cuban officials in Washington.

The official said Washington hoped to restore its embassy in Havana in "the coming months".

But he also voiced caution about the amount of change the discussions can bring, given the longstanding hostility between the two countries.

"It is hard to know exactly what will come out of this first conversation," the official said. "I am not oblivious to the weight of history."

'New era'

Four US Democratic senators and two congressmen concluded a three-day visit to Cuba on Monday, the first since Obama's policy shift. They met with Cuban Foreign Minister Bruno Rodriguez and anti-government dissidents, among others.

"I think he [Rodriguez] is open to every single issue from trade to communications to establishing relations in agriculture," Senator Patrick Leahy, a leader of the delegation, told reporters in Havana.

"Name an issue. They're involved. It's not like we're negotiating with countries we've been at war with," Leahy said.

Democratic Senator Dick Durbin voiced hope of a "new era of relations" with Cuba following the visit.

"This is historic. We were frozen in the same foreign policy with Cuba for over 50 years,

"Finally this president came to the realisation that that policy wasn't serving the best interests of the United States, of Cuba, or of the world," he said. "Now we are moving toward a new era."

US President Barack Obama reset Cuba policy on December 17, opting for engagement after more than five decades of US hostility towards the island nation's communist government.

Washington and Havana held 18 months of secret talks before announcing they would re-establish diplomatic ties and exchange prisoners.

Source: Agencies