"As soon as we had a minimum of data [about the case] we made a report to our contact with the Judicial Police and another to IGAS," said Vice Admiral Gouveia e Melo, who was speaking to journalists on the island of Porto Santo, in the Madeira archipelago, where he is keeping abreast of developments in the local vaccination plan.

Gouveia e Melo also asked the head of the Northern Regional Health Administration (ARS-N) "to immediately take steps to prevent this from happening again and to draw all the consequences. To all intents and purposes, it is an act of indiscipline".

In a plan "of this complexity and with this urgency and, being massive, there has to be discipline", he added.

An undetermined number of people without the requirements on this occasion have reportedly received vaccines in the area of the Eastern Porto Health Centres Cluster (ACES), in a case that came to the attention of the 'task force' on 24 June.

In a statement sent to Lusa news agency, the structure led by Gouveia e Melo said the situation "indicates the practice of contrary acts in the rules and instructions in force", adding that the ARS-N "has already requested the opening of an investigation process to find out what happened".

The ARS-N confirmed to Lusa the opening of the enquiry, but declined to give any details.

The 'task force' recalls, in the statement sent to Lusa, that "currently are being vaccinated, by central scheduling, by self-scheduling or by local scheduling, users aged 30 years or more and, in open house mode, users aged 50 years or more.

It adds that "vaccination of users below the age groups currently provided for is not foreseen, except for users with comorbidities defined in standard number 002/2021 of the Directorate General of Health, or other exceptions defined in the same standard".

The allegedly illegitimate vaccination was advertised on a social network by the Campanhã Parish Council, in eastern Porto, but an authorised source from the local authority said it merely publicised the initiative at the request of the area's ACES, exactly as requested.

The council's Facebook post said: "June 23 and 24, open vaccination from 5pm to 7.30pm at the Cerco vaccination centre".

According to the Directorate-General of Health, there are already nearly three million Portuguese with the complete vaccination against Covid-19, equivalent to 29 percent of the population.