Brazil's health ministry has said its website was hit on Friday by a hacker attack that took several systems down, including one with information about the national immunisation programme and another used to issue digital vaccination certificates.

The government put off for a week implementing new health requirements for travellers arriving in Brazil due to the attack.

Police said they were investigating the attack, according to a Reuters report.

The alleged hackers, calling themselves Lapsus$ Group” posted a message on the website saying that internal data had been copied and deleted. “Contact us if you want the data back,” it said, in an apparent ransomware attack.