Indian Prime Minister Narendra Modi was trapped on a flyover for 20 minutes by protesters in Punjab in what is being reported as a serious security lapse.
Mr Modi was on his way to a memorial in the northern state when the route was blocked by protesting farmers.
They were demanding the resignation of a cabinet minister whose son has been accused over the deaths of farmers.
“This was a major lapse in the security of the PM,” a statement from the federal home ministry said.
Mr Modi was also scheduled to address a rally in the city of Ferozepur, ahead of state elections.
But the home ministry said the prime minister’s convoy returned to the airport due to the security lapse.
The protesters were demanding the resignation of junior home minister Ajay Mishra, whose son has been accused in an incident that left eight people dead in October.
A car linked to Mr Mishra had ploughed into protesting farmers in Uttar Pradesh state, killing four men. Farmers alleged that the son, Ashish Mishra, was behind the attack, but the Mishras deny the allegation.
Mr Modi arrived at Bhatinda airport on Wednesday morning, and was supposed to fly to the National Martyrs’ Memorial and later to the rally in a helicopter.
But the trip was delayed by bad weather, and the convoy finally went by road when visibility did not improve. It got stuck some 30km (18 miles) from the memorial.
The home ministry said it has sought a detailed report from Punjab government on the “serious security lapse”.
“As per procedure, they have to make necessary arrangements for logistics, security as well as keep a contingency plan ready,” it said.