A UK health minister has denied the government is considering a two-week national lockdown, after a former World Health Organization expert said the coronavirus infection rate could be nearing 38,000 per day.

Edward Argar said there was “speculation in the press” that a new lockdown would be necessary to contain a rapid rise in infections but said the prime minister did not want such tough measures to be reimposed nationally.

On Wednesday night, the director of UCL’s Institute for Global Health, Prof Anthony Costello, tweeted: “I’m hearing from a well-connected person that government now thinks, in the absence of testing, there are 38,000 infections per day.”

He said an insider had told him that the chief medical officer, Prof Chris Whitty, favoured a two-week lockdown, but withdrew that comment on Thursday morning.

Argar told Sky News that proposals for a national lockdown was “not something I’ve seen within the department. The prime minister has been very clear on this: he doesn’t want to see another national lockdown, he wants to see people abiding by the regulations and making the local lockdowns work to get the infection rate down.”

He said the proposal for wider measures was “not something I’ve heard from Chris, and it’s something that the prime minister wants to see”.

Asked whether a national curfew could soon be needed, Argar told BBC Radio 4’s Today programme: “I don’t think we’re at a place where we would wish to see or need to see national-level restrictions.

“But that comes down as well to all of us following the rules, be they local lockdown guidelines or indeed the national law and guidance.”

New restrictions on social contact between households and a 10pm curfew on pubs are expected to be introduced in parts of north-east England in an attempt to curb rising coronavirus cases.

Nick Forbes, the leader of Newcastle city council, confirmed additional, temporary restrictions were being planned to prevent another full lockdown in the region.

Officials in London dealing with the virus fear tougher measures could soon be needed as infection rates continue to rise, with the city’s mayor warning of the country being on the edge of “a disastrous second wave”.

While the detected infection rates are much lower in the capital and, for instance, in Bolton and parts of the north-west, they have been rising. Lack of tests may mean the recorded rate of infections in London is artificially low, and plans are in place for tougher measures, the Guardian understands.

A spokesperson for the mayor, Sadiq Khan, said: “We are clearly on the precipice of a disastrous second wave. The government has wasted time over the summer to put proper plans and systems in place, which has unfortunately made the need for further restrictions over the coming weeks to control the virus more likely – either nationally or locally.

“There are a wide range of options available should they be needed, and decisions will need to be driven based on the science and data at the time.”