India's capital was barricaded and flooded with police and soldiers on Thursday for the latest and most sensitive leg of the protest-hit Beijing Olympic torch relay.
With India home to more than 100,000 Tibetan refugees, including exiled spiritual leader the Dalai Lama and radical youth groups, authorities have kept their plans for the scaled back relay route a closely guarded secret.
Indian police have voiced fears that in a bid to draw attention to China's crackdown on unrest in Tibet, activists may resort to the most extreme form of protest -- setting themselves on fire in front of TV cameras.
"Self-immolation bids by protesters are a major worry," a police official said. Reports said police were equipped with blankets and fire extinguishers.
Dozens of Tibetan protesters were detained overnight as the torch arrived from neighbouring Pakistan, an AFP photographer said, and activists promised more protests -- including a parallel torch relay -- during the day.
Indian officials have been forced to shorten the relay route in the capital, limiting it to a 2.3 kilometre (1.5 mile) jog along the Raj Path -- an avenue running from the presidential palace to India Gate.
"We have taken every precaution to ensure the event remains peaceful," junior home minister Shakeel Ahmed told reporters.
The event is reportedly expected to kick off some time around 4pm, although officials were refusing to confirm the exact time.
"If it was normal, we would have announced it at least 10 days earlier," said a torch relay organiser who asked not to be named. "But because of the present situation... the home ministry wants to be very careful."
Seventy Indian sports figures, entertainers and others are taking part in the run, including Bollywood actors Aamir Khan and Saif Ali Khan, tennis player Leander Paes and officials from China's embassy in New Delhi.
They will be guarded by about 16,000 police, paramilitary forces and an elite anti-terror unit. Traffic has been diverted, trains halted and government offices closed during the run, effectively paralysing the city centre.
The Indian Olympic Association has said members of the public were welcome to watch the run, but it was not clear how close police would allow people to get.
Jostling with the massive security contingent will be thousands of Tibetan demonstrators, according to members of Tibet's parliament-in-exile and other protest groups.
They have vowed to stage a peaceful and alternative run and a sit-in near India's parliament.
"We will have a parallel peace run," Youdon Aukatsang, a Tibetan parliament member, told AFP. "Our torch will be a symbol of our non-violent peaceful struggle. It is not our plan to disrupt the Olympic torch."
But other Tibet protest groups said they will try to breach the ring of security surrounding the flame.
"Chinese armed guards will be guarding the torch. We will go as close as possible and ask them to shoot us down," said
Dhondup Dorjee, vice-president of the radical, pro-independence Tibetan Youth Congress.
India has been home to the Dalai Lama since he fled Tibet after a failed 1959 uprising against Chinese rule in his homeland.
He has urged protesters to be "non-violent and peaceful," although China accuses him of trying to sabotage the Games. (AFP)
Indian capital locked down for tense torch relay