Qadri, a cleric who has dual nationality, refused to come out of the plane in Lahore, demanding that the aircraft should be taken to its original destination, Islamabad.
Qadri has came back from Canada to lead what he called a "revolution" against the government.
Information minister Pervaiz Rashid said that the plane was taken to Lahore as hundreds of Qadri's supports were present on the roads in Islamabad and there was real risk to his life.
Around 40 of Qadri's Pakistan Awami Tehreek (PAT) supporters sustained injuries in a clash with the police near the Benazir Bhutto International Airport in Islamabad, as they gathered to receive their leader.
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Police fired tear gas shells to disperse Qadri's supporters who had gathered at the blockades on Expressway, the main artery that leads to the airport near Koral Chowk, early this morning.
"I do not trust these murderers (Prime Minister Nawaz Sharif and his brother Shahbaz Sharif) and I will not leave the plane," Qadri said in telephonic address from the plane.
Some of the workers forcibly entered the airport premises, Geo TV reported.
Qadri had announced to land in the capital and lead a rally through the famous Grand Trunk Road to Lahore. The move resulted in panic in the government, which took elaborate measures to beef up security.
The airport in Islamabad was sealed yesterday evening and entry to the twin cities of Rawalpindi and Islamabad was restricted.