We live in a perilous time, in a perilous environment

Prime Minister Vajpayee

He said the inquiry would be completed in four months and he would "get to the bottom of the allegations".

The government is confronting a deepening crisis, with opposition parties disrupting parliament and demanding that the BJP-led coalition resign.

It has been under pressure since an Indian website released secretly filmed video footage implicating senior officials in corrupt arms deals.

Nation addressed

The BBC's Mike Wooldridge in Delhi says the focus of the judicial inquiry is still not clear.

In a special address, Mr Vajpayee promised that anyone found guilty would be punished, however high or low they may be.

But he also said that no deal was seen to have been struck in the video footage and no minister in his government was involved.

The prime minister said the ease with which undercover journalists had gained access to the defence ministry was deeply worrying.

"We live in a perilous time, in a perilous environment," Mr Vajpayee said.

The allegations, he said, had "served as a wake-up call for all of us".

Opposition regroups

Correspondents say Mr Vajpayee had hoped the resignation of Defence Minister George Fernandes would take the heat off the government.

But it has only served to galvanise the opposition who are demanding that the entire government step down.

Growing scandal

News website Tehelka releases video footage on Tuesday BJP president Bangaru Laxman quits after being implicated Vajpayee rejects Fernandes' offer to resign Trinamool Congress party withdraws support from coalition Fernandes steps down as resignation is accepted

"This is a government of thieves," shouted opposition MPs in the lower house of parliament, forcing its adjournment.

The prime minister has already lost the support of one of his alliance partners, the Trinamool Congress, and his parliamentary majority now stands at 20.

Several left-wing and secular parties have got together to plan an alternative government should the present one fall.

The main opposition Congress party is trying to come up with a similar strategy, but does not appear to have had much success.

'No wrongdoing'

On Thursday, Defence Minister George Fernandes handed in a letter of resignation and asked the prime minister to order an inquiry into the bribery allegations.

In a BBC interview, he denied any wrongdoing, but said he had to resign to uphold the morale of the armed forces.

The opposition has taken to the streets

"I resigned first and foremost because I was not able to make a clarification on the various charges that were levelled," he said.

Mr Vajpayee had initially rejected his colleague's resignation but changed his mind after the Trinamool Congress withdrew its support for his government.

Mr Fernandes did not appear on any of the video footage, but was implicated by association as the president of his Samata Party and close associate, Jaya Jaitley, was shown accepting money for a party conference.

Made by internet news website Tehelka.com, the film has already claimed the scalp of the ruling BJP president, Bangaru Laxman.

The defence ministry has suspended four officials implicated in the documentary and questioned several other senior officers.