The prime minister of St Vincent and the Grenadines has been treated in hospital after a demonstrator threw a rock at his head during an anti-vaccine protest led by nurses and other emergency workers on the eastern Caribbean island.

Ralph Gonsalves was bleeding profusely but is expected to recover, according to a statement from his office.

However, the prime minister will be flown to Barbados for further medical treatment including an MRI scan, Finance Minister Camilo Gonsalves told Parliament.

Authorities said Mr Gonsalves was injured when he stepped out of his car and tried to walk into Parliament amid a crowd of about 200 people that had blocked the entrance as they set roadblocks on fire.

“Such an act is to be unequivocally condemned,” his office said.

The attack was criticized by others including Ronald Sanders, ambassador to the Organisation of American States.

“This development in Caribbean politics is reprehensible,” he said.

Local media quoted Senator Julian Francis saying that a woman had been arrested.

The protest was organised by unions representing nurses, police and other workers who claimed that the government planned to mandate vaccines for certain employees.

Mr Gonsalves clarified that he would not make vaccines mandatory.