Tens of thousands of pilgrims are expected to bathe in the holy river Ganges on Sunday's occasion of "Mauni Amavasya" in the ongoing Maha Kumbh Mela.

"Mauni Amavasya" is the third important day of six bathing days at the Kumbh Mela after Makar Sankranti and Paush Purnima. For the Hindu pilgrims, Amavasya is the main day at the event.

The day marks the second Shahi snan of the mela after Makar Sankranti. The 55-day festival which is the world's largest religious gathering began on the auspicious day of Makar Sankranti in Allahabad, Uttar Pradesh, with thousands of devotees taking bath in the holy river.

For Mauni Amavasya, officials have made additional security arrangements.  

Apart from Uttar Pradesh police, more than 15,000 security officials drawn from Central paramilitary forces including Indo-Tibetan Border Police (ITBP), Central Reserve Police Force (CRPF), Border Security Force (BSF) and Rapid Action Force (RAF) and Provincial Armed Constabulary and Anti-Terrorist Squad (ATS) are keeping a close vigil, PTI reported.

"One dip in the river has the power to change life forever," 65-year-old Malti Devi from London, taking part in the festivities for the first time, told AFP.

"I'm not worried about the security or pollution. We're here to celebrate a festival that brings the rich and poor together," she added.

Shortly before the festival began, Prime Minister Manmohan Singh ordered the release of water from India's highest dam in Tehri for the biggest gatherings. He also warned of action against industries polluting the river.

"No one will be allowed to wash their clothes or throw plastic bags in the river on the main bathing day. Take a dip and move out of the water - those are the instructions we are giving," Manikant Mishra, an administrator at the mela, told AFP. 

A Hindu devotee takes a dip during the second
A Hindu devotee takes a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad February 10, 2013.
A sadhu or Hindu holy man rides a horse after taking a dip during the second
A sadhu or Hindu holy man rides a horse after taking a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad
Sadhus or Hindu holy men line up as they prepare to take a dip during the second
Sadhus or Hindu holy men line up as they prepare to take a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad
A Sadhu or a Hindu holy man rides a horse before he takes a dip during the second
A Sadhu or a Hindu holy man rides a horse before he takes a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad
People gather to watch as sadhus or Hindu holy men take a dip during the second
People gather to watch as sadhus or Hindu holy men take a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad
Sadhus or Hindu holy men line up as they prepare to take a dip during the second
Sadhus or Hindu holy men line up as they prepare to take a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad
Sadhus or Hindu holy men wearing marigold garlands line up as they prepare to take a dip during the second
Sadhus or Hindu holy men wearing marigold garlands line up as they prepare to take a dip during the second "Shahi Snan" (grand bath), of the ongoing "Kumbh Mela" or Pitcher Festival in the northern
Sadhus or Hindu holy men gesture as one of them holds a
Sadhus or Hindu holy men gesture as one of them holds a "trishul" or trident-shaped weapon after taking a dip during the second "Shahi Snan" of the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad
People gather to watch Hindu holy men take a dip during the second
People gather to watch Hindu holy men take a dip during the second "Shahi Snan" of the ongoing "Kumbh Mela" in Allahabad
A Sadhu or a Hindu holy man gestures before taking a dip during the second
A Sadhu or a Hindu holy man gestures before taking a dip during the second "Shahi Snan" (grand bath), during the ongoing "Kumbh Mela" or Pitcher Festival in the northern Indian city of Allahabad