Heathrow has made an improved pay offer in a bid to avert planned strikes by some security guards at the airport.

Around 1,400 members of Unite are due to stage a series of walkouts between May 5 and 27 following strikes over Easter.

Unite said the action would cause “inevitable disruption and delays” at a time when people were expected to be travelling to the UK for the King’s coronation.

A Heathrow spokesperson said: “We kept Heathrow running smoothly during the first 10 days of Unite’s failed industrial action, and 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.

“We have met with unions again and put forward an improved deal that gives colleagues the certainty of inflation-matching pay for two years – 10% this year and a CPI-linked increase in 2024, as well as a £1,150 lump sum.

“The majority of Heathrow colleagues do not want to strike. Unite needs to let their members vote on this deal.

“Each day that Unite continues to refuse to let colleagues vote on this offer costs colleagues money they deserve now.”

Unite’s regional officer Wayne King disputed this, and claimed the airport has shown a “stubborn refusal to make an offer that meets our members’ expectations”.

He added: “Our members have been crystal clear they are seeking a substantial permanent increase in pay.

“A small one-off lump sum payment will not alleviate the financial pressures our members are facing on a daily basis.”