The increase from 20 cases on Thursday is believed to be linked people who visited Sunny’s Sports Bar a week ago.
The bar remains closed until at least Tuesday, with 90 per cent of its staff self isolating.
A mobile testing unit offering pre-booked PCR tests was opened on Sunday at Fort William Shinty Club car park.
NHS Highland said contact tracing was continuing, with those who had come into contact with people who had contracted Covid required to self-isolate for ten days.
The Highlands are in level two of Covid restrictions, where bars can serve alcohol inside.
The health board said: ”There continues to be a large proportion of the cases that visited Sunny’s Bar in Fort William on May 22.
"All customers who visited the premises have been identified as close contacts and advised to self-isolate and seek a PCR test.”
Tests can be booked online via NHS Inform by selecting the option “I have been asked to book a test by my local council or health protection team”, or by calling 0800 028 2816.
Postal PCR kits are available.
NHS Highland public health consultant Dr Jenny Wares said: “This is a significant outbreak and we expect the case numbers to rise further.
"If you have been identified as a close contact, please self-isolate and get a PCR test.
"If you are identified as a close contact and your test is negative, you must continue to isolate for ten days.”