Portugal's Socialist Party (PS) won the European elections on Sunday, according to the official data of the Secretary-General of the Ministry of Internal Administration released.

Garnering 33.38 percent of the vote, the Socialist Party was followed by Social Democratic Party (PSD) with 21.94 percent and the Left Bloc (BE) with 9.82 percent, showed the data.

The abstention rate of the elections stood at 68.59 percent, the highest ever in the southern European country, compared with 66.09 percent in the last elections in 2014.

However, the European Union's (EU) participation rate in its 28 member states this year stands at 50.5 percent, the highest in the last 20 years and eight points above the previous votes, according to the European parliament.

The participation rate in the European elections this year exceeds the symbolic barrier of 50 percent and is about eight points higher than 42.6 percent registered five years ago.

Antonio Costa, Portuguese prime minister and secretary general of the PS, said that the rate of abstention in Portugal requires a reflection on what should be changed in the next five years so that the Portuguese could "feel part of the European project."

"I want to express my respect for those who did not vote," he told his supporters after winning the elections.

"This is the mandate that we will continue to fulfill, to grow and with certain accounts," the prime minister said.

Commenting on the high rate of abstention, Portuguese President Marcelo Rebelo de Sousa said that choosing not to choose is also a legitimate option and that the votes show "a clear pro-European majority."

Around 10.7 million voters on Sunday were to elect the 21 Portuguese members of the European Parliament in an election which 17 parties and coalitions competed.

The votes to elect the new 751-member EU assembly were held in each of the 28 current EU member states between May 23 and 26, with 427 million eligible voters across the continent.