Dressed in police uniform, up to four gunmen briefly seized hostages at the hospital, before escaping.

Dozens of people wounded last Friday's attacks on mosques in the city were being treated in the facility at the time of the assault.

The authorities said they were pursuing the suspects after one was wounded in an exchange of gunfire with police.

The gunmen were said to have failed in an attempt to reach a captured militant, injured in the mosque attacks, who was being treated at the hospital.

The assault came three days after suspected Sunni Muslim militants wearing suicide vests launched a gun and grenade attack on two Ahmadi prayer halls in Lahore and killed more than 80 worshippers from the minority religious community.

The gunmen fled after this latest attack, police said.

Lahore has been battered by a series of deadly attacks in the last year by militants who have declared war on both the government and minority groups in the country.