Pilots at Portugal's national airline have announced a 10-day walkout next month amid a spate of strikes by labor groups resisting government efforts to reform the transport sector and cut state company debts.

Around half of Portuguese train services were cancelled Thursday as workers with national rail company Comboios de Portugal walked out. Trade unions oppose government plans to privatize the rail company, whose debts in 2013 stood at more than 4.4 billion euros ($4.7 billion).

The Civil Aviation Pilots Union said late Wednesday its members would strike between May 1-10, grounding most of TAP Air Portugal's flights, to demand 20 percent of the company when it is privatized later this year.

The flag carrier has debts of just over 1 billion euros and is dogged by labor unrest.