The ceremony takes place three times a year, and failure to liquefy is seen as a portent of disaster

The blood of St Januarius has liquefied at the thrice-yearly ceremony – but the officiating cardinal fell ill.

Cardinal Crescenzio Sepe, the Archbishop of Naples, “blanched and had to sit down”, according to the news agency ANSA. The blood of the saint had reportedly liquefied, but the cardinal was unable to take the reliquary outside.

The liquefaction of St Januarius’s blood is said to take place three times a year: once in May, once in December, and once on September 19 – the feast day of the fourth-century bishop and martyr.

Many Neapolitans believe that when the saint’s blood remains solid, it portends disaster. It preceded, for instance, a famine in 1559, a cholera outbreak in 1833, the Allied bombing in 1944, and an earthquake in 1980.

According to a Catholic Encyclopedia entry from 1910, the blood normally liquefies in May and September, but in the December event the blood “remains solid more often than not”.

However, in recent years the marvel has been expected to take place on all three occasions, and there was alarm in the city after the blood failed to liquefy in December 2016.

The previous year, the blood half-liquefied in the presence of Pope Francis, only fully liquefying during the following week.