A landmark strike by British Airways pilots entered its second day on Tuesday with more travel chaos -- and no end in sight to the long-running dispute over pay.

British Airways (BA) pilots began a two-day strike on Monday, grounding nearly all of its flights and disrupting thousands of passengers in a dispute over pay.

International Airlines Group said an investigation into the theft of customers' data at its British Airways unit showed hackers may have stolen the personal information of a further 185,000 customers.

British Airways was battling its third day of disruption on Monday after a global computer system failure stranded thousands of passengers over a holiday weekend and turned into a public relations disaster.

British Airways warned Tuesday that customers could face further delays after a computer glitch in its global check-in system held up some flights, particularly in the United States, for hours.