Ending the suspense over status  of their talks for a possible amalgamation, Anil Ambani-led  RCOM and South African Telecom major MTN on Wednesday announced  extending their exclusive negotiations till July 21.

"RCOM and MTN have agreed to continue their negotiations in relation to such potential business combination, and have extended the period of exclusivity until July 21," RCOM said.

"It is to be noted that there is no certainty either on completion, or the timing of the said proposal," the statement added.

The two companies had first announced start of a 45-day exclusivity period on May 26, which ended on Tuesday.

Further, RCOM and MTN have cautioned its shareholders in dealing in the scrip of the companies.

Shareholders are advised to exercise caution in their dealings in the companies' securities dealings until a further announcement is made, the two firms said in separate regulatory filings.

Amid the announcement of extension, RCOM shares rose 4.57 per cent, at Rs 434.40 in morning trade on the BSE.