Jammu, Jul 25 (IANS): A fresh batch of 678 pilgrims left here on Tuesday to perform the ongoing Amarnath Yatra, an official said.

Over 2.50 Lakh pilgrims have so far performed the yatra which started on June 29.

"Another batch of 678 pilgrims left Bhagwati Nagar Yatri Niwas in an escorted convoy of 20 vehicles at 2.55 a.m.," the official said.

The pilgrims use the Jammu-Srinagar national highway to reach the Valley and all vehicles carrying pilgrims have to cross the Jawahar Tunnel before 3.30 p.m.

This has been done as a precautionary measure to ensure that pilgrims reach the two base camps of Pahalgam and Baltal before sunset.

Over 35,000 security personnel have been deployed to maintain law and order.

So far, 48 pilgrims have died.

Of these, 17 died in a road accident in Ramban district of Jammu region on July 16; eight were killed in a terror attack in Anantnag district on July 10; and 23 pilgrims have died of natural causes.

The Yatra will conclude after completing 40 days with the arrival of the 'Chari Mubarak' at the cave shrine on August 7.

Situated 3,888 metres above sea-level, the cave houses an ice stalagmite structure that waxes and wanes with the size of the visible moon.

Devotees believe the ice stalagmite structure symbolises mythical powers of Lord Shiva.