Sonia said Singh will be particularly remembered for his successful operation tenure on the Burma Front during World War II.
"His extraordinary contribution as an Air warrior would always be a source of inspiration for us," she said.
Congress vice-president Rahul Gandhi tweeted: "A soldier & diplomat par excellence. Marshal of IAF Arjan Singh's demise is an irreparable loss. India has lost a true hero. Deepest condolences (sic)."
Senior Congress leader and former minister P Chidambaram said Singh was the "epitome of courage and the embodiment of wisdom".