Local leaders in Lanarkshire have pleaded with the Scottish Government not to impose the toughest coronavirus restrictions in the area – warning they could have “potentially catastrophic impacts” on local businesses.

North and South Lanarkshire Council’s leaders have joined forces with the local NHS boss and police chief to argue against the possible imposition of Level 4 measures.

With Scotland introducing a new five-tier system of restrictions from Monday, First Minister Nicola Sturgeon will announce on Thursday which will apply in each of the country’s 32 local authority areas.

Final decisions on these have not yet been made, she said, adding the process for deciding the different levels for areas is “not easy”.

Ms Sturgeon also accepted there are “encouraging signs” coronavirus infections in Lanarkshire could be stabilising.

North and South Lanarkshire are the only two authorities where the First Minister is considering imposing the toughest restrictions straight away.

If the area is placed in Level 4, bars and restaurants would remain closed while non-essential shops would also have to shut, along with hairdressers, gyms, libraries and visitor attractions.

Speaking about the “severe” restrictions in Level 4, Ms Sturgeon pledged: “We will only use it if we think it is really necessary to get dangerously high levels of transmission that are threatening the overwhelm the NHS down in a quick and decisive manner.”

Her comments came as a letter from Lanarkshire leaders to the Scottish Government says “we do not believe the most up to date statistics support a move to Level 4”.

As they warned of “the significant additional harms and consequences”, they called on ministers to hold back from imposing such severe restrictions.

Instead they argued Lanarkshire should be placed in Level 3 – the area most of the central belt is expected to be in.

The letter, from North Lanarkshire Council chief executive Des Murray, his South Lanarkshire counterpart Cleland Sneddon, NHS Lanarkshire chief executive Heather Know and Lanarkshire chief superintendent Alan Waddell, says there is “emerging clear evidence in Lanarkshire that the very steep rise has been halted and that there is an indication that cases are falling to some extent”.

The local leaders add “the very rapid growth in cases is clearly slowing down” and it is “highly likely that this is a consequence of the increased restrictions previously imposed on hospitality and other sectors”.

Placing Lanarkshire in Level 4 would have “considerable implications” for the area and beyond, they claim, with “significant impacts on health and wellbeing, public services, and business and the economy”.

The leaders warn: “We are very concerned that businesses – who, as noted, have already complied with all the regulation and guidance in place – will suffer potentially catastrophic impacts.”

Conservative Central Scotland MSP Graham Simpson said a decision on Level 4 restrictions “must not be imposed on Lanarkshire against local community leaders and the scientific evidence”.

He added: “The local NHS, police and council leaders are unanimous that Lanarkshire must be in Tier 3.”

The row comes as leaders of Perth and Kinross Council are reported to be concerned their area could have the same level of restrictions as Dundee City Council – despite a lower number of cases.

Ms Sturgeon, speaking at the Scottish Government’s coronavirus briefing on Wednesday, stressed final decisions on the levels that will be imposed on different areas have not yet been reached.

She said: “Government has to reach these decisions and they are not easy decisions but they have to be taken by somebody.”

Ms Sturgeon insisted ministers “do not want to put any part of the country into Level 4 if it is not absolutely necessary”.

She added: “I very much hope that tomorrow we will not be putting Lanarkshire into Level 4.”