KARACHI, Pakistan » Ten months after the devastating attacks in Mumbai by Pakistan-based militants, the group behind the assault remains largely intact and determined to strike India again, according to current and former members of the group, Lashkar-e-Taiba, and a range of intelligence officials.

Despite pledges from Pakistan to dismantle militant groups operating on its soil, and the arrest of a handful of operatives, Lashkar has persisted, even flourished, since 10 recruits killed 163 people in a rampage through Mumbai, India's financial capital, last November.

Indian and Pakistani dossiers on the Mumbai investigations, copies of which were obtained by The New York Times, offer a detailed picture of the operations of a Lashkar network that spans Pakistan. It included four houses and two training camps here in this sprawling southern port city that were used to prepare the attacks.

Among the organizers, the Pakistani document says, was Hammad Amin Sadiq, a homeopathic pharmacist, who arranged bank accounts and secured supplies. He and six others begin their formal trial on Saturday in Pakistan, though Indian authorities say the prosecution stops well short of top Lashkar leaders.

Indeed, Lashkar's broader network endures, and can be mobilized quickly for elaborate attacks with relatively few resources, according to a dozen current and former Lashkar militants and intelligence officials from the United States, Europe, India and Pakistan.

In interviews with The Times, they presented a troubling portrait of Lashkar's capabilities, its popularity in Pakistan and the support it has received from former officials of Pakistan's military and intelligence establishment.

Pakistan's chief spy agency, the Inter-Services Intelligence directorate, or ISI, helped create Lashkar two decades ago to challenge Indian control in Kashmir, the disputed territory that lies at the heart of the conflict between the nuclear-armed neighbors.

Pakistani officials say that after 9/11 they broke their contacts with the group. No credible evidence has emerged of Pakistani government involvement in the Mumbai attacks, according to an American law enforcement official.

But a senior American intelligence official said the ISI was believed to maintain ties with Lashkar. Four Lashkar members, interviewed individually, said only a thin distance separated Lashkar and the ISI, bridged by former ISI and military officials.

One highly placed Lashkar militant said that the Mumbai attackers were part of groups trained by former Pakistani military and intelligence officials at Lashkar camps. Others had direct knowledge that retired army and ISI officials trained Lashkar recruits as late as last year.

“;Some people of the ISI knew about the plan and closed their eyes,”; said one senior Lashkar operative in Karachi who said he had met some of the gunmen before they left for the Mumbai assault, though he did not know what their mission would be.

The intelligence officials interviewed insisted on anonymity while discussing classified information. The current and former Lashkar militants did not want their names used for fear of antagonizing others in the group or Pakistani authorities.

But by all accounts Lashkar's network, though dormant, remains alive, and the possibility that it could strike India again makes Lashkar a wild card in one of the most volatile regions of the world.

India and Pakistan have fought three wars since they were created by the bloody partition of British India in 1947. Whether they begin again the long journey toward peace or find themselves eyeball to eyeball, nuclear arms at the ready, depends in no small measure on the actions of this shadowy group.

A new attack could reverberate widely through the region and revive nagging questions about Pakistan's commitment to stamp out the militant groups that use its territory.

It could also dangerously complicate the Obama administration's efforts in Afghanistan. Success there depends in part on avoiding open conflict between India and Pakistan, so that Pakistan's military can focus on battling the Taliban insurgents who base themselves in Pakistan.

Even so, American diplomatic efforts to improve India-Pakistan relations have been stillborn. So sensitive is the Kashmir issue that Indian officials bridle at any hint of American mediation.

Meeting on the sidelines of the U.N. General Assembly, the two sides failed to restart talks last weekend, with India demanding greater steps by Pakistan to prosecute those responsible for the Mumbai attacks.

The dossiers show that at the level of the police, the two countries can cooperate, and have exchanged DNA evidence, photographs and items found with the attackers to piece together a detailed portrait of the Mumbai plot.

But the files are laced with barbs and recriminations, reflecting the acid tenor of their relations. Despite pledges to work together to fight terrorism, the Pakistani and Indian intelligence services are not on speaking terms, according to officials in both countries and the United States. The gaps heighten the risks of a new attack substantially, American officials fear.

“;The only cooperation we have with the Pakistanis is that they send us their terrorists, who kill our people, and we kill their terrorists,”; said a senior Indian intelligence official in an interview.

Asked how much his agency communicated with its Indian counterpart, a senior Pakistani intelligence official made an O with his thumb and forefinger.

“;Zero,”; he replied.