And similar fines could also be issued for breaching rules on gatherings.
In a specially convened sitting next Tuesday, States Members are due to debate a proposal to make it compulsory for all over-12s to wear masks in public places such as shops and other businesses, unless they have an exemption.
Up until now wearing a mask has been advised rather than mandatory.
The proposed new rule comes after the government repeated strong advice for senior pupils and teachers to wear mouth and nose coverings when they are moving around communal indoor areas in schools.
The guidance is aimed at students in Years 11, 12 and 13. It does not apply to outdoor communal areas or classrooms.
Yesterday another case of Covid-19 was confirmed at Victoria College and all sixth formers have been asked to go home and remain there until the direct contacts of the student have been identified. The affected student is isolating at home with the rest of his household.
If mask wearing does become compulsory, there could be exemptions for disabled people or those who, for medical reasons, cannot cover their mouths.
There would also be exceptions in ‘unusual circumstances’ – such as if someone had to enter a shop to avoid danger.
If no exemptions apply then the offence would carry a ‘level 2’ fine of up to £1,000.
In his proposition, Health Minister Richard Renouf said that a ‘level 1’ fine of up to £100 was not considered high enough to deal with deliberate or malicious breaking of the rule.
And discussing new proposals on gatherings, the minister said: ‘The legislation will also offer a way to manage gatherings of people to limit the spread of Covid-19. Gatherings have been the subject of guidance since the lockdown and safe-distancing arrangements were lifted, but this has not been enforceable in law.
‘The regulations will allow orders (called gathering control orders) to be made to place a limit on the size and characteristics of gatherings that are allowed. This restriction is given effect by granting powers to enforcement officers to disperse gatherings over the permitted size or those outside the permitted characteristics.’
If approved, fines could be issued to those who ‘wilfully refuse’ to disperse if ordered to do so.
The new guidelines for schools were issued by the Scientific and Technical Advisory Cell after an increase in cases among older students.
It recommends mask wearing for everyone except those who cannot put on, wear or remove one because of a physical or mental illness or disability.
There would also be an exemption for anyone speaking to a person with hearing problems who relies on lip-reading or clear facial expressions to communicate.
Deputy medical officer of health Dr Ivan Muscat said: ‘While there is growing evidence that younger children are not super-spreaders, the risk of transmission is greater in older children and young adults, which explains why we have limited face coverings to this group.’
Education Minister Tracey Vallois added: ‘When we made the decision to reopen schools in early June, I was clear that the safety of students, staff, and their families was our priority.
‘As the Covid-19 situation is changing, so is the guidance we are issuing. This new advice will help keep our schools safe without disrupting the teaching and learning experience.’