MADRID, April 23 (Xinhua) -- Air traffic controllers at Barcelona's El Prat airport have announced a series of 24 hours strikes which will begin on June 20 to coincide with the start of the summer holiday season, local media reported on Monday.

The air traffic controllers'union USCA has not given the exact days of the planned stoppages.

The union claimed that instead of working shifts of five days followed by three days off, controllers are currently on duty for six days with just two days for rest, placing them under excessive strain with the subsequent risks to passenger safety.

"The shortage of supervisors in the control towers has become chronic and, despite the calls to hire new recruits, they won't be in place in time to ease the intense work schedule of high season," explained the USCA, with spokesman Pau Mari telling the media the forecast was not pessimistic, but "realistic."

The strike will not just affect flights in and out of Barcelona, but also to the popular tourist destinations such as the Balearic Islands and other airports on the east coast of Spain, which serve regions such as the Costa Blanca, given that many flights to those destinations fly though airspace controlled from Barcelona.