LONDON -- Britain is anxious about the spread of the novel coronavirus variant first detected in India and rules out nothing when it comes to re-introducing local restrictions, Prime Minister Boris Johnson said on Thursday.

Johnson has laid out a "cautious but irreversible" route out of lockdown for England, with the next step planned for next week. He has warned new variants, such as the B.1.617.2 variant, pose a risk to that plan.

"We are anxious about it - it has been spreading," Johnson said, adding that there would be meetings later on Thursday to discuss what to do.

"We're ruling nothing out," Johnson said.

There has been a surge in cases of the variant in north-west England, and local politicians have called for a change in policy so any adult in the area can get a shot, even if they don't meet age-based priority criteria.

The local council of the town of Blackburn said additional COVID-19 vaccination clinics would open next week to speed up shots, but denied reports that vaccines would be widely available to all over-18s in the area, saying eligibility for the shots would follow current guidance.

After England's initial COVID-19 lockdown, Johnson had sought a regional approach to restrictions, which ultimately failed, and two further national lockdowns followed.

He has sought a nationwide approach to the easing of restrictions this time, and reiterated that, despite the local surges in variant cases, he hoped restrictions would end across the whole nation in June.

"At the moment I can see nothing that dissuades me from thinking we'll be able to go ahead on Monday and June 21 everywhere," he added, referring to further steps to ease lockdown.

(Reporting by William James and Alistair Smout; writing by Guy Faulconbridge, editing by Andy Bruce and David Gregorio)