It echoes recent statements by American generals, who have increased their warnings that militant safe havens in Pakistan are threatening efforts in Afghanistan. The study was funded by the U.S. Defense Department.
"Every successful insurgency in Afghanistan since 1979 enjoyed safe haven in neighboring countries, and the current insurgency is no different," said the report's author, Seth Jones. "Right now, the Taliban and other groups are getting help from individuals within Pakistan's government, and until that ends, the region's long-term security is in jeopardy."
Pakistan's top military spokesman rejected the findings.
The study, "Counterinsurgency in Afghanistan," found some active and former officials in Pakistan's intelligence service and the Frontier Corps -- a Pakistani paramilitary force deployed along the Afghan border -- provided direct assistance to Taliban militants and helped secure medical care for wounded fighters.
It said NATO officials have uncovered several instances of Pakistani intelligence agents providing information to Taliban fighters, even "tipping off Taliban forces about the location and movement of Afghan and coalition forces, which undermined several U.S. and NATO anti-Taliban military operations." No timeframes were given.
The report said Pakistan's intelligence service and other government agencies provided Taliban and other insurgents with training at camps in Pakistan, as well as intelligence, financial assistance and help crossing the border.
When asked in an Associated Press interview last month what the state of the insurgency might be in 2013, the outgoing NATO commander in Afghanistan, U.S. Gen. Dan McNeill, said: "If there are going to be sanctuaries where these terrorists, these extremists, these insurgents can train, can recruit, can regenerate, there's still going to be a challenge there."
Afghan President Hamid Karzai has pleaded with the world community to address the issue of militant sanctuaries in Pakistan. Afghan intelligence officials say young, uneducated males are recruited in the border tribal areas to become suicide bombers and fighters. After battles or attacks in Afghanistan, militants flow back into Pakistan to rest and rearm, officials say.
Pakistan -- which supported the Taliban regime in Afghanistan before the Sept. 11 attacks -- denied it is supporting the insurgents, but acknowledged the problem of militant infiltration.
"Whenever these kinds of places are identified or pointed out, action is taken against these places and there are umpteen examples in the past where the actions have been taken against these insurgents, or, for that matter, foreigners," said Pakistan military spokesman Maj. Gen. Athar Abbas. "Therefore, we reject this claim of sanctuaries being aided by Pakistan's army or intelligence agencies."
Pakistan Interior Ministry chief Rehman Malik said Monday that he met with Karzai in the Afghan capital over the weekend, and the two sides agreed to set up biometric screening at key border checkpoints.
Malik said tens of thousands of people cross each day without any documentation.
"They go without any checking -- no passport, no documentation. It's a free for all," he told reporters. He said the new computerized system would begin operating within two weeks.
Nevertheless, he defended Pakistan's efforts to police the border, saying the government had deployed 120,000 troops and had set up five times more border posts than there are on the Afghan side.
Malik expressed willingness to share intelligence on extremists and conduct joint operations with Afghan security forces. He denied that Pakistan would strike peace deals with terrorists in order to calm Islamic militancy on its own soil.
Pakistan has insisted it is only pursuing negotiations with militant groups willing to lay down their arms, and it has relied partly on tribal elders to mediate. A handful of deals have already been struck.
U.S. officials say attacks where American troops operate in eastern Afghanistan have gone up significantly since those deals were reached earlier this year.
The study said that besides the Taliban, other major militant groups find sanctuary in Pakistan. These include al-Qaida, Gulbuddin Hekmatyar's radical Hezb-i-Islami group and the Haqqani network, led by Jalaluddin Haqqani and his son, Siraj.
"These insurgent groups find refuge in Pakistan's Federally Administered Tribal Areas, North West Frontier Province, and Baluchistan Province," RAND said in a news release. "They regularly ship weapons, ammunition and supplies into Afghanistan from Pakistan, and a number of suicide bombers have come from Afghan refugee camps based in Pakistan."
The report also called on the U.S. and its allies to help build the Afghan security forces, particularly the police, and to improve the quality of local governments, especially in rural regions.
It also claimed that Afghanistan's police are incompetent and "almost uniformly corrupt," echoing frequent criticism of the police by international officials here.
The U.S. is spending billions of dollars to train and equip the Afghan police, but the efforts are still years away from being completed.