Belgian lawmakers Wednesday questioned PM Alexander De Croo and Foreign Minister Hadja Lahbib for allowing officials from Iran and Russia to attend a mayors' convention in Brussels last week.

Lahbib especially is under scrutiny for having approved visas requests while Iran and Russia are under international sanctions and only three weeks after Belgian NGO worker Olivier Vandecasteele was released from an Iranian jail. He was exchanged in a controversial move with a former Iranian diplomat convicted in a Belgian court of leading a terror plot in Europe and serving a long prison sentence.

De Croo and Lahbib said they didn't want to risk a diplomatic row with Iran close to the release of Vandecasteele and three other Europeans, but lawmakers from opposition as well as coalition parties contest that reasoning.

When in Brussels, the Iranian delegation filmed Belgo-Iranian lawmaker Darya Safai and Iranian opposition members, Belgian national broadcaster RTBF reported.

Safai, who was a prominent activist in Iran before fleeing to Belgium in 2000, said she no longer felt safe in Belgium.

Tehran' mayor, Alireza Zakani, is known as a hardline Iranian politician, who was a member of the Revolutionary Guard’s Basij militia.

The opposition has called for Lahbib's resignation, while extreme-right opposition party Vlaams Belang also asked for De Croo's resignation.

State secretary for external relations of the Brussels government Pascal Smet resigned on Sunday over the all-expenses paid trip.

Reporting by Reuters