A Ryanair Boeing 737-8AS plane takes off at the Riga International Airport, Latvia March 15, 2019. REUTERS/Ints Kalnins

(Reuters) - Irish-based carrier Ryanair said on Tuesday its pilots based in Portugal have voted for a labor agreement for the next four years, taking another step to head off any risk of another round of damaging strikes ahead of its peak summer season.

The agreement governing pay and conditions was negotiated between Ryanair and the Portuguese pilot union SPAC to cover all of the airline’s directly employed pilots in Portugal, the carrier said.

Ryanair has been struggling with labor relations since it bowed to pressure to recognize unions for the first time almost a year ago.

The airline had said in October that it had reached an agreement with its Portuguese pilots on seniority and home base issues, looking at the time to end a damaging series of strikes that had hurt its business.

It had said that the Portuguese deal - covering issues such as leave allocation and promotion - would allow talks with Portugal’s SPAC union on a full collective labor agreement.

Separately, Ryanair said on Tuesday that passenger traffic grew 9 percent to 10.9 million in March.