At least 31 women and children were killed and nearly 50 injured in a stampede at an Islamic religious gathering in Karachi on Sunday, official sources said.

"I can confirm you that 27 have been killed and 50 injured in the stampede," Minister Shabbir Kayamkhani said in a brief statement, adding that a state of emergency had been declared in all hospitals.

Police officials feared the casualty list was like to rise but refused to speculate.

"Of the 50 injured, 20 have been discharged after providing treatment but the condition of eight is very critical and the doctors were working hard to save their lives," he added.

As the minister and police confirmed the toll to 27, three elderly women and a minor girl succumbed to wounds raising the tally of death to 31, including 23 women and eight children.

"Three elderly women died because of head injuries while a minor girl expired due of severe internal injuries," duty officer at the government-run Abbasi Shaheed Hospital said.

The stampede occurred at an Islamic center of a Sunni Muslim group in down town Karachi and was triggered when a boy fell on the exit and his mother tried to save him from being crushed to death, eyewitnesses said.

"Thousands of women were leaving for a rally after attending the gathering to mark the birthday of the Prophet Mohammad," Karachi police spokesman Zahid Hussain said.

The weekly Sunday gathering attracted nearly 50,000 women and children because of Eid Milad-un-Nabi (celebrated to mark the birth and death anniversary of Prophet Mohammad), that falls on Tuesday.