The United States has rebuffed a Cuban demand to be taken off the US list of state sponsors of terror as they opened a second round of historic talks to restore long severed diplomatic ties.

US Secretary of State John Kerry said on Friday that the terror designation, in place since 1982, would be reviewed separately but was not a matter for negotiation.

"The state sponsored terrorism designation is a separate process, it is not a negotiation," he said.

"And that evaluation will be made appropriately and nothing will be done with respect to the list until the evaluation is completed."

A top Cuban foreign ministry official, Gustavo Machin, had argued before the start of the latest round of talks that the terror designation was in "contradiction" with full diplomatic relations.

The issue has practical as well as symbolic importance to the Cubans, because the designation complicates its access to the global banking system.

Friday's talks at the State Department are only the second since President Barack Obama and Cuba's President Raul Castro surprised the world in December with their decision to restore ties after more than a half century of Cold War enmity.

The hope is that within the coming months, both nations will agree to reopen embassies in each other's capitals and appoint full-fledged ambassadors.

Currently they operate through so-called interests sections in Havana and Washington.

The US president is due to attend the Summit of the Americas in Panama on April 10-11, which Cuba will also attend for the first time.

Observers say that both nations, long mired in tension stemming from the Cold War, are keen to relaunch full diplomatic relations around that date.

An initial round of talks in Havana last month - the highest level since US-Cuban relations were severed in 1961 - broke the ice but ended with little sign of a breakthrough.

Kerry described the talks as technical in nature - "fairly normal negotiations with respect to movement of diplomats, access, travels, different things".

The negotiating teams met at the State Department just before 9:00am local time (1400 GMT).

Roberta Jacobson, assistant secretary of state for Western Hemisphere affairs, faced Josefina Vidal, the Cuban foreign ministry's director for US affairs.

Source: AFP