A parliamentary delegation from Pakistan, which is now in New York, pitched this idea during its five-day visit to Washington last week, Dawn online reported on Wednesday.
"A greater South Asia is already emerging," said Senator Mushahid Hussain Syed, in one of his interactions with the media.
"This greater South Asia includes China, Iran and the neighbouring Central Asian republics."
He described the China-Pakistan Economic Corridor as the key economic route linking South Asia with Central Asia.
The Gwadar port, he said, would be the nearest warm water port, not only for China but also for the land-locked Central Asian states.
"We want India to join this arrangement as well," said Hussain, an offer Indians are unlikely to accept as they are comfortable with the advantage that SAARC provides them.
Last month, India used its influence in SAARC to isolate Pakistan when it announced that it would not attend the regional group's 19th summit, scheduled in Islamabad on November 15 and 16.
India cited Pakistan's involvement in the September 18 terrorist attack at an Army camp in Uri town of Kashmir, in which 19 soldiers died, as the reason for its decision to boycott the summit.
India has blamed Pakistan for the attack, a claim which Islamabad has denied. Other Saarc nations -- Afghanistan, Bangladesh, Bhutan and Sri Lanka -- joined India to boycott the meeting.
According to Dawn, the boycott has led to an indefinite postponement of the summit and exposed Pakistan's isolation within the region.
"Apparently, the showdown forced Pakistan to conclude that in its present shape, Saarc will always be dominated by India. That's why they are now talking about a greater South Asia," said a senior diplomat, confirming reports that Pakistan is actively seeking a new regional arrangement.
"Pakistan hopes that this new arrangement will give it more room to manoeuvre when India tries to force a decision on it," said another diplomat.
Diplomatic observers in Washington said the proposed arrangement also suits China as it is worried about India's rapidly growing influence in the region.
They argued that China can play an important role in persuading Central Asian republics and Iran to join the new arrangement.
But, according to the observers, Saarc members will have little interest in supporting the idea.
There is not much benefit for Bangladesh, Nepal and Sri Lanka in joining a land route far from their borders and Dhaka as well as Colombo have their own ports.
The member that is likely to get the most benefits from a greater South Asian alliance is Afghanistan, which is technically a land-locked Central Asian nation.
But observers believe that Afghanistan is too closely linked to India to join any arrangement that hurts New Delhi's interests.
Afghanistan's presence in Saarc, however, justifies Pakistan's argument that Central Asian nations can be included in a greater South Asia.
Saarc member states imposed a stipulation for Afghanistan to hold general elections, which were held in late 2005, enabling the country to join the group as its eighth member in April 2007.
But, as a South Asian diplomat pointed out, even if a greater South Asia became reality, there's no guarantee that its members would support Pakistan in its disputes with India.
"Many Central Asian states have strong ties with India and Iran too has problems with Pakistan," the diplomat said.