Bharti Airtel and South African telecom major MTN on Thursday extended their exclusive talks for a complex $23-billion cash-cum-stock deal by a further one month to September 30. This is the second time that the negotiations have been extended, raising concern among investors over the terms of an agreement that would create the world?s third-largest telecom firm by subscriber base with revenues of over $20 billion.

Sources said MTN shareholders want Bharti to improve on its offer and that the latter was mulling a 5-10% sweetening. Whether such a revised proposal would be acceptable to the MTN management and stockholders was not clear. Earlier, however, Bharti group deputy CEO Akhil Gupta had categorically said there was no question of increasing the offer price.

Sources said pricing issues had forced both companies to extend their talks by a month to August 31 the last time around. Issues like representation on the board and governance structure are also believed to have held up an agreement.

For its part, a Bharti statement said, ?Discussions between the parties regarding the potential transaction continue to progress satisfactorily.?