'SingTel is part of the team that is looking at issues together with Sunil and Akhil,' the source said on Monday, referring to Bharti's founder and chairman Sunil Bharti Mittal and joint managing director Akhil Gupta.

The source said it was premature to speculate if SingTel - which is Bharti's largest shareholder with over a 30 per cent stake - would provide any form of financial support to Bharti for the bid as the deal was evolving.

'It depends on the final structure of the deal. Valuations are not firm. It may be the case that no financial support is needed. There are no details at this stage. It's a very complex deal,' said the source, who declined to be identified because the details were not finalised.

SingTel, South-east Asia's largest phone company, declined to comment. Last Tuesday, it confirmed that Bharti was holding talks with MTN, after Bharti and MTN said last Monday they were in talks which may or may not lead to a deal.

Bharti also said in a separate statement it had not made any offer to buy the whole or part of MTN.

The Asian Wall Street Journal, quoting an unidentified source, said on Monday that Bharti was considering raising its offer to around 175 South African rand (S$31.3) a share for control of MTN, and an official bid could come this week.

Faced with a tiny domestic market, state-controlled SingTel has spent $18 billion in recent years buying stakes in mobile operators in high-growth Asian countries such as India and in the bigger Australian market.

SingTel, Singapore's largest listed firm, derives about three-quarters of its sales and two-thirds of pretax earnings outside the country. -- REUTERS