Former Prime Minister Atal Bihari Vajpayee, undergoing treatment for urinary tract infection at the AIIMS here, is responding well and his vital parameters are stable, hospital officials said on Tuesday.

Vajpayee was admitted to the All India Institute of Medical Sciences on Monday.

"His condition is stable. He is responding to treatment and is on injectable antibiotics. All vital parameters are stable. He will continue to be in hospital till the infection is controlled," AIIMS media and protocol division chairperson Aarti Vij said.

Vajpayee's hospitalisation triggered VIP visits including that of Prime Minister Narendra Modi, Bharatiya Janata Party (BJP) President Amit Shah and Congress President Rahul Gandhi on Monday, followed by Vice President M. Venkaiah Naidu and MDMK leader Vaiko on Tuesday.

A team of senior doctors under the supervision of Randeep Guleria, Director, AIIMS, is conducting the tests on Vajpayee, who is bed-ridden for many years. Guleria, a pulmonologist, has been a personal physician to Vajpayee for long.

The BJP on Monday said Vajpayee was admitted on the advice of doctors for routine check-ups and investigations.

Modi called on Vajpayee on Monday evening and interacted with his family. He spoke to doctors and enquired about the former Prime Minister's health. Modi was at AIIMS for about 50 minutes.

Rahul Gandhi was the first to visit the hospital to check on Vajpayee's health. Health Minister J.P. Nadda also visited, followed by Amit Shah and Modi.

Vajpayee, 93, who was Prime Minister briefly in 1996 and then from 1998 to 2004, retreated from active politics over the last decade due to failing health.