Thousands of passengers faced disruptions as strike action by Qantas ground staff forced cancellations or delays to 55 flights across Australia. Tuesday\'s nationwide walkout by some 4,000 baggage handlers, caterers and freight workers in a dispute over pay and conditions saw staggered four-hour stoppages throughout the morning peak period.Half way through the morning, 28 flights have been cancelled and 27 delayed, Qantas said on its website. More than 6,000 passengers are expected to be affected, the carrier added, but the chaos has been limited by the airline deploying larger aircraft and using management staff in ground roles.The cancellations were all domestic services and included 11 flights from Sydney, 10 from Melbourne, four from Brisbane, two from Canberra and one from Adelaide. The strike follows a breakdown in contract talks and the airline\'s recent announcement of a major Asia-focused restructure which will see 1,000 staff sacked. Olivia Wirth, Qantas group executive of government and corporate affairs, said progress could only be made if the union returned to the negotiating table and stopped industrial action.\"What it does take is for this sort of action to stop,\" she told reporters. \"If they are serious about these discussions and representing their members they need to continue their negotiations.\"Qantas, which last month reported an annual net profit of Aus$250 million -- double that of the previous year -- is also locked in a bruising industrial dispute with pilots and engineers over pay and conditions.They are already undertaking low-level industrial action but have threatened to escalate their campaign.