"My heartfelt congratulations to Vajpayee Sahib and his family on the day he receives the Bharat Ratna. It was an honour to serve under him," the former Jammu and Kashmir chief minister wrote on twitter.

Omar, the working president of National Conference, was Minister of State for External Affairs in the Vajpayee-led NDA government.

"As his (Vajpayee's) MOS MEA, I had the occasion to travel with him to 4-5 countries. Memories of those trips on Air India One I'll always cherish a lot," he added.

In a departure from tradition, President Pranab Mukherjee will confer the Bharat Ratna on Vajpayee at his Krishna Memon Marg residence on Friday.