"The prime minister wanted someone young yet very experienced to head the foreign ministry. Salman Khurshid was the top choice," said another senior official in the prime minister's office on condition of anonymity.
Khurshid has held several ministerial positions and has served as a junior foreign minister in 1990s.
Speaking to reporters after a swearing-in ceremony for the new ministers, Singh said he expected that his new team would remain in office up until the next general election which is due in spring 2014.
"Probably this is the last reshuffle," Singh said at the presidential palace in the capital New Delhi.