The Centre on Wednesday directed all Union Ministries and Departments to clear Air India's dues immediately.
An office memorandum from the Finance Ministry's Department of Expenditure said: "Recently, the Government of India has decided to disinvest Air India, and the process of disinvestment of Air India and Air India Express is ongoing."
"Air India has stopped extending credit facilities on account of purchase of air tickets. Therefore, all Ministries or Departments are directed to clear Air India's dues immediately."
"Air tickets from Air India, may be purchased in cash till further instructions."
In 2009, the Centre had mandated that Central government officers travel via Air India for all official purposes including availing of LTC.
On Monday, conglomerate Tata Group entered into a share purchase agreement with the Central government for buying out the latter's stake in national carrier Air India, Air India Express, and AISATS.
Earlier, a Letter of Intent was issued to the Tata Group.
After the SPA, Tata Group would need to fulfil the conditions precedent in the agreement before taking over the airline. The rest of the transaction is expected to be completed by December.
Tata Sons' subsidiary Talace emerged as th e highest bidder for the national carrier under the divestment process.
Talace had quoted an enterprise value of Rs 18,000 crore for 100 per cent equity shareholding of the Centre in Air India along with that of Air India Express and AISATS.