Jammu:Another batch of 1,871 pilgrims left Jammu city on Sunday in a secured convoy to perform the Amarnath Yatra. "As many as 1,505 males and 366 females on Sunday left the Bhagwati Nagar Yatri Niwas in Jammu city in 40 buses and 16 light motor vehicles for Kashmir Valley," a senior police official told IANS in Jammu. "They left around 4.40 a.m. in a convoy secured by ROPs (road opening parties) and mobile protection provided by the security forces." The Amarnath Yatra started on Saturday and around 9,000 pilgrims began the mountainous trek to cave shrine from north Kashmir Baltal and south Kashmir Nunwan (Pahalgam) base camps. The shrine is situated 3,888 metres above the sea level in Himalayas in Kashmir. It houses an ice stalagmite structure called the 'Lingam' that wanes and waxes with the phases of the moon. Devotees believe the 'Lingam' symbolises mythical powers of Lord Shiva. There have been a number of attacks on the security forces during the last one month on the strategic Jammu-Srinagar national highway which is the only surface link used by the yatris to reach the two base camps in Anantnag and Ganderbal districts of the valley. Union Home Minister Rajnath Singh attended the special Puja inside the cave shrine and had 'Darshan' of the ice 'Lingam' on Saturday. He has advised better coordination among the security forces to provide foolproof security to the yatris. The 48-day long yatra this year will end on August 17 coinciding with Shravan Purnima and Raksha Bandhan festival.