UK's blue-chip index was set for its worst monthly decline in over a year on Tuesday, as a warning by Moderna's chief executive over the Omicron coronavirus variant hammered pandemic-exposed sectors like banks and commodities.

The FTSE 100 declined 1.2%, on track to end November with losses of more than 3%, while the domestically focussed mid-cap index fell 1.1%.

Moderna's head Stéphane Bancel told the Financial Times that existing COVID-19 vaccines were unlikely to be as effective against the Omicron variant as they have been against the Delta version, sparking a sell-off in global stocks.

Drugmaker AstraZeneca, which also makes COVID-19 vaccines, fell 1.6%.

British airline easyJet slid 2.1% after reporting some softening of trading in the first quarter on COVID-19 outbreaks and the discovery of the Omicron variant. Broader travel and leisure stocks declined 2.3%. 

"It almost feels like minus 10% for travel stocks is the new black," said Max Kettner, multi-asset strategist at HSBC.

"Sentiment around reopening stocks has hit absolutely rock bottom now and it's not just been a function of last Friday, but it has been a function of two or three months already."

Rate-sensitive banks fell 1.1%, while oil stocks dropped 2.7% as crude prices declined on fears that the heavily mutated Omicron variant would spark fresh lockdowns and dent global growth. 

Meanwhile, data showed costs were rising at the fastest rate in over 20 years for firms in Britain's services sector, putting the Bank of England in a tough spot as they face rising inflation and economic risks at the same time.

The internationally focussed FTSE 100 has underperformed its domestic counterpart so far this year, gaining 8.3% compared with the 9.6% jump in the FTSE 250 index.

"You really want to short FTSE 250 and actually go back to the FTSE 100, the more export oriented international market," added Kettner, pointing to cracks building in the UK economy.

Money transfer company Wise Plc jumped 9.9% after it reported a 33% rise in half-year revenue, while British media company Future Plc soared 15.7% on lifting its 2022 outlook. 

(Reporting by Bansari Mayur Kamdar in Bengaluru; Editing by Subhranshu Sahu and Uttaresh.V) ((;))