Van der Linden, who also held talks with human rights activists, discussed the political situation ahead of the 6 November parliamentary elections.
The Council of Europe has called on the Azerbaijani authorities to ensure that the polls are fair and democratic. Tensions are running high in the run-up to the elections.
Several attacks against opposition activists have been reported in recent days amid official charges that the leader of an antigovernment youth movement had received foreign money to carry out a revolution.
Citing similar allegations, pro-government parties have refused to enter into dialogue with the opposition. Van der Linden is due to meet with President Ilham Aliyev before leaving Azerbaijan tomorrow.