Jakarta – United Development Party chairman Suryadharma Ali invited all Islamic parties to join his party, excluding, however, the Prosperous Justice Party (PKS) and National Mandate Party (PAN) in his invitation.

"PKS and PAN are not Islamic parties," Suryadharma told reporters after the PPP's 39th anniversary celebration at the Istora Senayan in Central Jakarta on Sunday.

He declined to explain why he deemed PKS and PAN as not being Islamic parties, despite the fact that both PKS and PAN are fundamentally known as being very closely affiliated with Islam.

In his remarks, Suryadharma, who also serves as Indonesia's minister of religious affairs, highlighted the importance of Islamic people joining hands with PPP in becoming a "house for all Indonesian Muslim people."

"Muslims are the majority in Indonesia. However, the political power of Muslims has become a minority. What has gone wrong? For that reason, the PPP opens its doors to all Islamic parties, whatever their school of thought, to join the party," he said.

"The PPP was established by ulemas to build a civil and democratic society. The party also encourages religious life with respect to religious tolerance [to other groups]," Suryadharma said as quoted by tempo.co on Sunday.

Late last month Suryadharma became the subject of criticism after he called the Shiite branch of Islam heretical because in his view it deviated from mainstream Islamic teachings.

Suryadharma had previously made similar statements about the Islamic Ahmadiyah sect, which he also called heretical, and urged its followers to return to the "true teachings of Islam". Many feared that his statements as a top official in charge of the religious affairs could provoke violence against minority groups.