The US Embassy in the Cuban capital of Havana has resumed all visa-processing services after suspending them six years ago due to a series of health incidents among its staff.

The embassy started processing all immigrant visa categories on Wednesday. The move comes as the US government grapples with a surge in illegal migration by Cubans.

The embassy stopped issuing visas and slashed other services in 2017 after many staff reported unexplained symptoms such as hearing loss and headaches.

It was initially suspected that the ailments were caused by sonic attacks. But in an interim report last year, the CIA said its investigation found no evidence of any foreign organization being responsible for the symptoms.

People seeking visas formed a queue outside the embassy on Wednesday. One of them said she's very grateful that visas are being issued again.

US media say the country is now anticipated to grant at least 20,000 visas a year to Cubans.

In the year to the end of September 2022, more than 220,000 Cubans tried to enter the US illegally. This is nearly six times the figure for the same period the previous year.

US State Department spokesperson Ned Price said the resumption of full visa services is "a significant step in the restoration of consular services in Havana."

He said the US remains "committed to facilitating the safe, orderly, and regular migration of Cuban citizens to the United States."