Pakistan, Feb. 3 -- Cuba has confirmed it is in contact with the United States (US) and is open to dialogue, but insists that core issues such as its constitution and socialist system of government are not negotiable, according to a senior Cuban diplomat.

Carlos Fernandez de Cossio, Cuba's deputy foreign minister, told Reuters on Monday that Havana was ready for "a serious, meaningful and responsible dialogue" with Washington, though he stressed that exchanges had not yet reached the level of formal negotiations. "We have had exchanges of messages, we have embassies, we have had communications, but we cannot say we have had a table of dialogue," he said.

In a separate interview with The Associated Press, de Cossio added that dialogue co...