UK scientists have warned that Covid-19 reinfections were "to be expected" amid a recent surge in the number of fresh cases, according to a media report.

The conclusion by researchers on the Covid-19 Genomics UK Consortium is based on what is known about people's immunity to other coronaviruses that cause the common cold, Xinhua news agency quoted the report by the Guardian newspaper as saying on Saturday.

It was unclear how soon people who had recovered from Covid-19 could become vulnerable to reinfection, but emerging reports showed the timeframe was "relatively short", said the report.

Currently, there are seven types of coronavirus that infect humans.

Among them, Sars, Mers and Sars-Cov-2, the virus that causes Covid-19, are considered the deadliest.

The four others cause common colds and can reinfect people six months after they have recovered, according to the report.

Nearly two dozen cases of suspected or confirmed Covid-19 reinfections emerged across the globe, but the real number is thought to be far higher, since most were not recorded, it added.

With 16,171 new Covid-19 cases, the UK's overall infection tally has increased to 705,428, while the death toll stands at 43,579.

The country's coronavirus reproduction number, also known as the R number, has edged up slightly, according to latest government figures.

The government's Scientific Advisory Group for Emergencies (SAGE) said the R number is now between 1.3 and 1.5, up from last week which was between 1.2 and 1.5.

If the R number is above one, it means the number of cases will increase exponentially.