London, Dec 15 : Strikes planned by hundreds of workers at London's Heathrow airport will go ahead on Friday, union leaders said, with further dates announced for action over the Christmas and New Year period, as per media reports. Unite said ground handlers at Britain's biggest airport had rejected the latest "miserable" pay offer from their employer, Menzies, The Guardian reported. The workers will go ahead with a 72-hour strike beginning at 4 a.m. on Friday and a further 72-hour strike is planned, beginning on December 29 and ending at 3.59 a.m. on January 1. The dispute involves more than 400 workers employed by Menzies as ground handlers operating from Heathrow terminals 2, 3 and 4, The Guardian reported. The post-Christmas stoppage would also coincide with the planned strike by Border Force staff, Unite said. Unite General Secretary, Sharon Graham, said: "This is a classic case of an employer that can fully afford to pay workers a fair pay increase but has chosen not to. "Menzies needs to stop making excuses and make a pay offer that meets our members' expectations." The strike is unlikely to cause widespread disruption for passengers departing from Heathrow, with neither British Airways, which operates around half of all Heathrow flights, nor Virgin Atlantic affected. A Heathrow spokesperson said: "We are aware of industrial action proposed by Menzies colleagues from December 16-18. "We encourage airport partners who would be affected to continue with their contingency planning and we will support them to minimise the impact on passengers." During previous similar industrial action in November, Heathrow said no flights were cancelled as a result of the strike, The Guardian reported. The Border Force strike is likely to affect only inbound flights and while it will probably cause delays and longer queues through immigration for returning holidaymakers after Christmas, airlines have said they are confident that they will be able to operate flights without widespread disruption. The additional strikes by Unite will add to the general wave of industrial action over the winter, with nurses striking on Thursday and more rail strikes starting again on Friday, The Guardian reported. /IANS