Security guards at London's Heathrow airport to strike in May

Security guards at London's Heathrow airport will strike for a further eight days next month in a dispute over pay, their union announced Wednesday, as various UK industrial action rumbles on.

Around 1,400 security officers, who walked out for 10 days over Easter, will stage their latest stoppage at Heathrow's Terminal 5 on May 4-6, 9-10 and 25-27, the Unite union said.

It warned of "inevitable disruption and delays", as the start of the walkout coincides with people expected to travel to the UK for King Charles' coronation on May 6.

The announcement comes on the same day Britain's Office for National Statistics (ONS) revealed UK inflation held stubbornly above 10 percent last month, further fuelling the worst cost-of-living crisis in a generation.

It has prompted strike action by various public and private sector workers, from nurses to port workers, as the double digit inflation rates of the past year spark demands for increased wages.

"Our members have been crystal clear they are seeking a substantial permanent increase in pay," Unite regional officer Wayne King said of his members' dispute with Heathrow.

The airport's management insist they have been engaged in talks with Unite for months and had improved a 10 percent pay rise offer with a further £1,150 lump sum this year.

Heathrow claims Unite is refusing to put the revised offer to its members.

An airport spokesperson said Terminal Five's operations ran "smoothly" during the previous industrial action and that "passengers can have confidence that we will do so again this time".

"We will not let Unite disrupt the flow of visitors to the UK during such an important period for the country," the spokesperson added.