New Delhi, Feb 9 (IANS) Amid speculation about China's keenness to join the tri-nation pipeline that involves Iran, India and Pakistan, the Iranian envoy Tuesday said Tehran 'can't wait indefinitely' for New Delhi to join the pipeline project.

'Our negotiations with Pakistan have gone ahead to the stages of implementation... We have kept our doors open for India to join the project,' Iranian Ambassador Seyed Mehdi Nabizadeh told reporters here.

'It (Iran) will not wait indefinitely,' the Iranian envoy said.

'There must be a time limit.'

The Iran-Pakistan-India gas pipeline is stuck in differences between New Delhi and Tehran over pricing of the Iranian gas and security of the pipeline that is expected to pass through volatile Pakistani territory.

Last week, Iran's Foreign Minister Manouchehr Mottaki had said that China was keen to join the gas pipeline project.