New Delhi, Aug 11 (IANS): Manmohan Singh has become the third longest-serving prime minister of India as he completed 2,273 days in office Wednesday.

India's first prime minister Jawaharlal Nehru tops the list at 6,130 days, while his daughter Indira Gandhi remains the second longest-serving prime minister with 5,829 days in office.

"There are no special celebrations for the day. The prime minister is following his routine schedule," an official in the Prime Minister's Office (PMO), who declined to be identified, told IANS.

"The main functions he celebrates related to his office are the anniversaries of the UPA (United Progressive Alliance) government.They are all well publicised functions attended by UPA chairperson Sonia Gandhi and other leaders," the official added.

Manmohan Singh, 77, moved to the thrid slot Wednesday, replacing his predecessor Atal Bihari Vajpayee, who had been in office for 2,272 days over three terms.

Vajpayee was prime minister for 13 days in 1996 and for 2,256 days in the second and third terms during 1998-2004.

The Manmohan Singh-led UPA-1 (2004-2009), at 1,826 days, holds the second position among the longest-serving central governments. Indira Gandhi's second stint (March 18, 1971-March 24, 1977) tops the list at 2,198 days. This became possible for Indira Gandhi as her government's tenure was extended during the emergency.

After Nehru, Manmohan Singh is the only prime minister to have been re-elected on completion of a full five-year-term.

"Dr. Singh does not bother about ornamental statistics. His focus is always on dedication and quality of work," said the PMO official.