According to the BBC, BA said the problem was not a cyber attack but was instead related to a hardware issue.
Long-haul flights continued to operate with minor delays, but all short-haul services were cancelled until midday Saturday (26 February).
Passengers travelling from Gatwick and London City airport also reportedly faced some delays due to the issues.
A BA spokesperson reportedly said: "We are extremely sorry that due to the continuing technical issues we are facing we have regrettably had to cancel all short-haul flights from Heathrow today [Saturday] until midday.
