A total of 568 suspects has been detained since Monday as part of an anti-terror operation across Turkey following a terror attack in Istanbul, the Interior Ministry said Tuesday.

Suspects detained include officials of the opposition Peoples' Democratic Party (HDP) and its sister party, the Democratic Regions Party (DBP), local Hurriyet reported.

They were charged with involvement in activities by the outlawed Kurdistan Workers' Party (PKK) and spreading terror propaganda, the ministry said in a statement.

On Monday, the police raided the offices of HDP and DBP and detained 235 suspects in 11 provinces.

The police made 333 more arrests on Tuesday as the operation expanded to 28 provinces.

Interior Minister Suleyman Soylu said Tuesday that security forces has cracked down on PKK's drug trade, which serves as the group's biggest source of income.

The latest raid followed two explosions that rocked downtown Istanbul late Saturday and killed 44 people and wounded 155 others.

A total of 13 suspects linked to the bombings have been arrested so far.

The government accuses the HDP of having links to the PKK, which is listed as a terrorist organization by Turkey, the United States and European Union.

source: Xinhua