The Wall Street Journal quoting two people familiar with the situation said Bharti has contacted Middle Eastern sovereign wealth funds for additional cash to back its MTN bid for a majority stake.
"However, there is no agreement yet," WSJ said quoting one of the persons in an article published in its online edition.
Further, the paper quoted another person and said that Bharti has already negotiated about $12 billion in financing from a group of banks that includes Standard Chartered plc, but the deal may require more resources.
According to media reports, Singapore Telecom, which holds 30 per cent in Bharti Airtel, is also actively involved in the talks to acquire stake in MTN and could provide some assistance in this big ticket acquisition if it takes place.
When contacted, a SingTel spokesperson declined to comment.
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Last week, both Bharti and MTN announced that they are in "exploratory talks".
The race for MTN is hotting up with Etisalat, the telecom incumbent from the UAE has also expressed interest in the South African company.
"We are evaluating MTN, among other companies," Etisalat Chairman Mohammed Omran said.
Earlier, media reports said that Bharti is looking at acquiring 51 per cent stake in MTN for about $19 billion. It is also reportedly planning to raise the bid per share to 175 rand a share or $22.63 per share.
If the deal takes place, it would create world's sixth largest mobile company with 130 million subscribers in more than 20 countries.