Centrica PLC (LON:CAN) shares were on the back foot in Thursday’s early deals as British Gas workers start a five-day strike.
Up to 7,000 British Gas workers could strike, according to reports.
It comes amid a row over contracts with the utility group reported seeking to force pay cuts by threatening sackings, via ‘fire and rehire’.
The GMB union claim that British Gas had tarnished its reputation and added that the strike would cause massive disruption to customers in the depths of winter, during a cold snap.
British Gas owner Centrica meanwhile said it has done everything it can to avoid industrial action.
"While we've made great progress with our other unions, sadly the GMB leadership seems intent on causing disruption to customers during the coldest weekend of the year, amid a global health crisis and in the middle of a national lockdown," a Centrica spokesperson said.
In the wake of suggestions earlier this year that it could cut 5,000 jobs, the company has converted around 83% of its workforce onto new contract terms.
Centrica shares fell 0.66p or 1.45% to change hands at 50.04p.