ISLAMABAD: After anti-government protesters and law enforcement personnel clashed in the federal capital, Pakistan Tehreek-i-Insaf (PTI) and Muttahida Qaumi Movement (MQM ) late on Saturday night announced to observe a Youm-i-soug (day of mourning) on Sunday.

MQM leader Haider Abbas Rizvi, one of the members of the mediating committee with the PAT, speaking to DawnNews said: “The situation at the moment is extremely painful. There is no Pakistani right now whose hand is not on his heart.”

“Our effort was to prevent a law and order situation for which the government will have to use force. Now we have no choice but to stand with the victims. For this reason, the MQM has announced a countrywide strike.”

Later, MQM chief Altaf Hussain demanded Prime Minister Nawaz Sharif to voluntarily resign from his position, DawnNews reported.

Read more: Violent clashes in Islamabad, dozens injured

Police fired tear gas and rubber bullets at thousands of protesters led by PTI chairman Imran Khan and Pakistan Awami Tehreek (PAT) chief Dr Tahirul Qadri.

Some 25,000 people began to march on the prime minister's house late Saturday after talks with the government mediated by the powerful army failed to end the impasse.

Violence broke out after the protesters attempted to remove containers in front of the President House, using a crane.