Up to 18 more cases of the Indian variant of coronavirus have been detected in Watford, new figures reveal.

Public Health England has been tracking the spread of the B.1.617.2 mutation – which originated in India – by testing positive Covid-19 cases across the country for an "S-gene".

According to Hertfordshire’s director of public health, Jim McManus, the Indian variant is not the dominant variant anywhere in Hertfordshire.

PHE data shows 18 positive cases of the S-gene were identified in Watford by May 25, from samples taken in the week to May 21.

This came after the health body identified 11 cases the week before.

The majority of areas in England have now reported at least one case.

Health Secretary Matt Hancock said up to three-quarters of new coronavirus cases nationally are the Indian variant, though he stressed the vaccines are helping to keep hospital admissions down.

The data shows 11,403 S-gene positive cases were recorded in England between the start of March and May 25.

Of these, 1,301 (11 per cent) were in the East of England – the third largest proportion of England's nine regions, but well behind the North West, where there were around 5,700 cases.

Meanwhile Watford has seen a rise of cases of the virus, particularly within the last four days, prompting Hertfordshire County Council to issue a warning.

Read more: 'Covid alert' issued for Watford after new spike in cases

The county council posted an alert on its Facebook page this afternoon, which read: "Case rates are continuing to rise in Watford.

"Please take extra care if you’re visiting indoor hospitality & entertainment, meeting family & friends indoors and enjoying more of the things you’ve missed. Remember ‘hands, face, space & fresh air’. If we all play our part, we can all keep doing the things we love."

Government figures show 55 positive cases were recorded in Watford between Monday and Thursday this week, including 22 on Tuesday.

However Mr McManus has suggested the Indian variant is not to blame for the latest spread in Watford.

The rise in cases comes as official Public Health England figures show there were no (zero) Covid patients being cared for at West Hertfordshire Hospitals NHS Trust as of Tuesday (May 25).

It is the first time zero patients have been recorded since data began being published on March 20 last year.

Mr McManus told the Observer: "The Indian variant of COVID-19 is not yet the dominant variant anywhere in Hertfordshire. However, the proportion of cases of the Indian variant is growing and it appears that nationally this variant will become dominant within the next few weeks.

"The number of coronavirus cases is rising in Watford, with cases spread right across the borough. The 'coronavirus alert' on social media seeks to inform our residents and encourage them to keep doing the basics over the Bank Holiday weekend.

We should all continue to wear a face-covering when required, wash our hands regularly and maintain social-distancing and, if meeting people indoors, make sure the venue is well-ventilated.

"Meeting outdoors for now is much lower risk if the weather allows. It is also absolutely critical to get the vaccine when you can or when offered it, take a test twice-a-week, and self-isolate if you are told to.

"To find out more about tests and the options available, people can go to www.hertfordshire.gov.uk/rapidtest."