Millions of people face summer holiday hell after staff at Britain's biggest airport yesterday announced two strikes during the getaway season.

Families hoping to escape the gloomy weather and head for the sun have been warned flights from Heathrow could be "severely" affected next week.

British Airways World Cargo, logistics operator operates the Centre for

handling in Heathrow Airport (UK).

Thursday night the Unite union, which represents 275 cargo staff who voted for industrial action, confirmed the strike will start at 6.30 a.m. next Wednesday, June 27, and continue until 6.29 a.m. on Saturday, June 30.

A second walkout is planned from Wednesday, July 4 until Saturday, July 7.

Although the strike only affects workers carrying freight cargo, and not baggage handlers, the potential for passenger chaos remains huge at Heathrow.

Experts say the proposed walkouts will severely disrupt the loading of cargo onto aircraft, which is a huge source of revenue for the major carriers. Every item of cargo has to be specially configured, weighed and checked before the plane is cleared for take-off.

Last night Unite officer Kevin Hall said: "Loading cargo is an intricate part of an airline's business. If cargo and vehicles are in the wrong place because of the strike this is going to have adverse knock-on effects. Our members, faced with rising household bills, have been driven to take this action, which could be severely disruptive to flights at Heathrow as the summer holiday season kicks off. Swissport has refused to negotiate on a pay rise for the year 2010/2011."

Union officials and Swissport management are set to meet for eleventh-hour talks at conciliatory service on Monday.(AviationPros/AC)