According to a senior railway official, the train, which was expected to reach Old Delhi railway station at 3:30 am, is now expected to reach the national capital at around 8 am.
On Thursday, Pakistan had stopped the Samjhauta Express at the Wagah border, citing security concerns, following which an Indian crew and guard escorted the train to Attari on the Indian side, officials said.
Pakistan on Wednesday announced its decision to downgrade diplomatic ties with India.
Citing New Delhi's move to bifurcate Jammu and Kashmir and revoke Article 370, Islamabad said that it would be expelling the Indian High Commissioner and suspending bilateral trade with New Delhi.
Hundreds of passengers from both sides of the border were stranded for several hours waiting for security clearances to be completed following the disruption in the train service that connects Delhi and Lahore.
After several hours of waiting, the Samjhauta Express headed for Lahore departed from Attari at 6:41 pm.
The "Samjhauta" Express train, named after the Hindi word for "agreement", comprises six sleeper coaches and an AC 3-tier coach.
On July 22, 1976, the Samjhauta Express train service was started under the Simla Agreement that settled the 1971 war between the two nations. The train runs from Delhi to Attari on the Indian side and from Lahore to Wagah on the Pakistan side.
( With inputs from IANS )