Pakistan has flatly denied that Indian troops crossed the de facto border in the disputed territory of Kashmir to help the earthquake relief effort.
India and Pakistan have eased travel restrictions
The Indian army says its troops have twice crossed the Line of Control at the invitation of Pakistani soldiers.
Correspondents say images of Indian troops helping on the Pakistani side would be embarrassing to the authorities in Pakistan.
Both sides claim Kashmir and have fought two wars over the territory.
A Pakistani army spokesman told the BBC that reports of Indian troops helping Pakistani troops rebuild their bunkers were "unimaginable" and "purely fabricated".
"None of our bunkers on the [Line of Control] were destroyed by the earthquake so there is no possibility that Indian troops have helped Pakistani troops. This is pure fabrication," Major General Shaukat Sultan insisted.
According to the first reports from the Indian army, the Pakistani soldiers invited the Indians to help them rebuild some of their bunkers after sleeping in the open in increasingly cold temperatures.
Normally, such a crossing would have resulted in bloodshed, says the BBC's Sanjeev Srivastava in Srinagar.
On Thursday an Indian army spokesman insisted that Indian troops had crossed over to the Pakistani side.
But he said they had only handed over tools such as picks and shovels and had not helped reconstruct any bunkers.
On Wednesday Indian army officials expressed frustration that they could not help more with the relief effort.
One soldier pointed towards Muzaffarabad, the devastated capital of Pakistani-administered Kashmir and said Indian helicopters could reach it with supplies within 15 minutes.
With the bridge connecting the Indian and Pakistani sectors of Kashmir destroyed, Delhi and Islamabad both also waived travel restrictions to allow some Kashmiri families to return home through the Wagah border in Punjab.
Our correspondent adds that there is growing demand for easier access across the divided valley, allowing people to cross over to try to help loved ones on the other side.
The Pakistan military spokesman also said that rumours to the effect that the earthquake might have caused some damage to Pakistan's nuclear installations were also baseless.
"The nuclear installations are built in a such a way so that they can even survive air attack. So to say that the earthquake might have caused some damage to the installations is completely untrue," he added.
A new earth tremor thought to be an aftershock has been felt in the Pakistani capital, Islamabad.
There were no immediate reports of damage or casualties from the quake recorded at 0123 local time Thursday (2023 GMT Wednesday) by the US Geological Survey.
With a magnitude of 5.6 and centring on an area 135km north of the city, it was the strongest tremor recorded since the weekend in Pakistan which has felt several dozen aftershocks.