The Pakistani government was aware of potential attacks at the Wagah border with India, sources have claimed.
It is believed that the Research and Analysis Wing – Pakistan's largest spy agency - had issued warnings of an imminent suicide attack targeting the evening flag ceremony at the Wagah border on 15 October, two weeks before a blast killed at least 55 people, anonymous sources told the Indian Express.
The warning came after Pakistan's Rangers enhanced their forces and put in place new defensive structures.
Inspector general of police Mushtaq Ahmad Sukhera said an 18-year-old suspected suicide bomber blew up his explosive jacket around 5.50 pm in a crowd, after he failed to gain entry into a secure area closer to the ceremony.
The explosion occurred in a car park about 500m from Wagah on Sunday (2 November), as people were leaving after watching the daily flag-lowering ceremony. The blast also left more than 100 people injured.
Thousands of people gather in Wagah every day to watch an elaborate ceremony as the border closes.
India's Border Security Force and Pakistan agreed to suspend it on security grounds and to allow mourning.
Three terror groups claim responsibility
The Pakistani Taliban have claimed responsibility for the blast.
However, other two terror groups, Jundallah and Jamaat-ul-Ahrar, also claimed responsibility, with the latter saying more attacks are to be expected.
"We will soon release the video of this attack," Jamaat-ul-Ahrar's statement read. "This attack is the revenge of the killing of those innocent people who have been killed by Pakistan Army, particularly of those who have been killed in North Waziristan."
Investigations are ongoing.