London, May 26 : IT issues have forced the cancellation of 43 British Airways flights scheduled to depart and arrive into London's Heathrow airport. The flights were cancelled as of 5 p.m. on Thursday evening, the BBC reported citing aviation data firm Cirium as saying. About 800 flights in total were scheduled to fly from the UK on Thursday. In a statement, the British flag carrier apologised for the cancellations and said it was fixing the "technical problems" which caused difficulties with online check-in. British Airways added that affected customers had been contacted and offered options, including a refund or rebooking onto an alternative flight with the airline or another carrier. In recent years, the airlines has suffered several IT failures, including one in December 2022 that saw dozens of long haul flights being cancelled in the week before Christmas, the BBC reported. A major outage in 2017 had stranded 75,000 passengers over a holiday weekend. Passengers also faced delays due to an IT issue in February this year, days after flights had been cancelled due to Storm Eunice. The latest incident also came as security guards at Heathrow Airport began a three-day strike over pay on Thursday. The airport has however, said that operations will not be affected. /IANS