A memorial service in Delhi for the victims
A meeting of the Cabinet Committee on Security on Thursday decided to offer what was described as "all assistance required".
Foreign Minister Jaswant Singh told the Times of India that Delhi would provide logistical help or act as a staging ground for a US military strike.
"There have been contacts at all political, executive and operational levels about this," Singh was quoted as saying.
As the hunt for those responsible gathers pace, there is a growing belief the United States will target Afghanistan, where prime suspect Osama bin Laden is sheltering.
'All assistance required'
"In using the formula 'all assistance required', it is to be understood that this means military as well as intelligence," a senior official told the AFP news agency.
But he added that India not receive any formal request from the Americans for assistance.
Although India was traditionally allied with the Soviet Union during the Cold War, ties between Washington and Delhi have warmed considerably in recent years.
India provided operational help to the United States during the Gulf War
India's Prime Minister Atal Behari Vajpayee reiterated on Friday that his country stood fully behind the United States in its hunt for those behind the attacks.
In a solemn address on national television, Mr Vajpayee gave a gloomy assessment of the economic fall-out from any retaliatory military action.
But he did not spell out how India would support Washington's military response.
Focus on Pakistan
Washington is taking diplomatic steps to build a global coalition against terrorism.
They have already received valuable support from its Nato allies and even from Russia and Central Asian countries.
In particular, the US is focussing on India's long-term rival, Pakistan.
US officials have handed over a list of specific requests to Pakistan's President Pervez Musharraf.
Pakistan, one of the few countries that recognize Afghanistan's ruling Taleban, wields considerable influence with the hardline militia.
Correspondents say any action against Afghanistan by US forces would be virtually impossible without co-operation from Islamabad.