New Delhi, July 29 (IANS): Thousands of passengers were badly hit Monday afternoon after a two-hour technical snag forced Delhi Metro trains on one of its key lines to crawl, causing overcrowding at many stations.

The problem led trains on the Blue line connecting Dwarka with Noida City Centre and Vaishali in Uttar Pradesh to halt for up to 10 minutes at major stations, leading to passenger pile up, officials said.

Commuters complained that the situation was at its worst between Dwarka in west Delhi and Rajiv Chowk, the network's busiest inter-change in the city centre.

The snag was detected around 1.30 p.m. and set right at 3.12 p.m., a Delhi Metro official said. But it took a while for normalcy to return.

The official blamed the problem on overhead electrification that transmits energy to trains on a stretch between Shadipur and Patel Nagar .

It also failed the air-conditioning system, making journey in the packed coaches "a sweltering hell", a breathless commuter said.

The crowd was menacingly thick at Rajiv Chowk, through which both the Blue and Yellow lines pass.

"This is too much," moaned an exhausted Digambar Sharma, who boarded a packed train at Rajiv Chowk. "The compartment I was in was crammed as everyone on the platform wanted to get into the train."

Trains also stopped for 5-10 minutes on numerous occasions, said Devansh, a student.

"It took me one hour to reach Noida Sector 16, a distance which usually takes just 30 minutes," he said.

Normally, a train plies every three minutes between Dwarka and Yamuna Bank. From there, alternate trains go to either Vaishali or Noida City Centre.

A Metro official said regular announcements were made at all stations and in trains about the delay.

But commuters felt that mere announcements served no purpose and that Delhi Metro needed to have a quicker response system to address "technical problems".

"As the Metro network spreads and footfalls increase, problems are bound to occur more often. Delhi Metro needs to restore disrupted services much quicker than it is now doing," said Deepak Kumar.

Kumar took an agonising three hours to travel from Dwarka Sector 12 to Noida Sector 16 -- unlike the normal 75 minutes.

The 49-km Blue line covers 43 stations in some of the most populous parts of the capital and is the longest Delhi Metro route.