UPDATE 1-MTN says Bharti Airtel talks still in progress

* Discussions still underway

* Shareholders should exercise caution

(Adds details)

JOHANNESBURG, July 6 (Reuters) - South Africa's MTN Group Ltd (MTNJ.J) said on Monday it was still in discussions with India's Bharti Airtel (BRTI.BO) but gave no further details about the talks, which could lead to a full merger.

MTN said in a cautionary announcement, which it is obliged to issue under JSE stock exchange rules, that talks were still in progress.

MTN, Africa's biggest cell phone operator by subscribers, and Bharti, India's leading cellular firm, have revived talks aimed at creating the world's No. 3 wireless group with more than 200 million subscribers and combined revenue of $20 billion. [ID:nLP34850]

The chief executive of MTN's biggest shareholder, state pension fund Public Investment Corporation (PIC), told Reuters in June the fund supported the talks but said there was "room for improvement" on the price.

Bharti Airtel's (BRTI.BO) chairman said last week the group was not working on sweetening the deal, but did not rule it out.

The two companies are in exclusive talks until the end of July. MTN shares closed 0.59 percent higher at 120 rand on Monday. (Reporting by Rebecca Harrison; Editing by Marius Bosch)