"The event of most people singing the national anthem has been postponed because of security issues," a Punjab government spokesman said.
The event, scheduled to be held on Monday, was put off for an indefinite period.
The record for the maximum number of people singing the national anthem is currently held by India.
A senior police officer told PTI that intelligence agencies had told the government about possible attempts by terrorists to sabotage the event to be held on the grounds of the Punjab University in Lahore.
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"The government cannot provide a soft target to the Taliban in the current scenario," he added.
Punjab Education Minister Rana Mashhood, however, gave a different reason for the postponement. "We needed more space for setting the world record. The venue turned out to be small," he said.
Earlier, the Punjab government finalised preparations for the singing of the national anthem by 150,000 people as part of a youth festival.
The government directed vice-chancellors of universities and principals of colleges to send the maximum number of students to the venue.