By Lesley Wroughton

NEW DELHI (Reuters) - Pakistan needs to join other nations in fighting terrorists within its borders, U.S. Secretary of State John Kerry urged on Tuesday, saying Islamabad should not feel isolated by talks between the United States, India and Afghanistan next month in New York.

Kerry announced the Afghanistan initiative on a visit to New Delhi for the annual U.S.-India strategic dialogue. His show of support for his Indian hosts marked a change from Washington's usual neutrality regarding India and Pakistan, South Asia's two nuclear-armed antagonists.

Tensions between Pakistan and India have spiked of late, as an uprising in Indian-administered Kashmir killed more than 60 people and injured thousands. Pakistan and India each claim the disputed territory in full but rule it only in part.

Washington has long urged India and Pakistan to reopen talks to resolve the tensions and Kerry will discuss the issue with Indian Prime Minister Narendra Modi on Wednesday.

Addressing a news conference, Kerry denounced terrorism in all its forms. He said the perpetrators of attacks on Indian soil - in Mumbai in 2008 and at an airbase in Punjab last January - should be brought to justice.

"We cannot and will not make distinctions between good and bad terrorists," Kerry said. "Terror is terror no matter where it comes from, (or) who carries it out."

India accuses Pakistan of responsibility for both attacks. Pakistan is trying suspects in the Mumbai attacks, in which 166 people died. Investigations into this year's airbase attack have so far been inconclusive.

India's minister for external affairs, Sushma Swaraj, struck a similar note, saying there was a "meeting of minds" between her and Kerry on terrorism, which she described as the foremost threat to international peace and security.

Kerry said the United States would open the trilateral talks on the sidelines of the U.N. General Assembly in New York next month. Its goal is to stabilize Afghanistan, whose U.S.-backed government is struggling to contain Taliban rebels.

India has provided a little over $2 billion in economic assistance to Afghanistan in the last 15 years and said recently it would deliver more arms to Afghanistan.

Kerry said the United States was working to address tensions in Afghanistan's fragile coalition of President Ashraf Ghani and Chief Executive Abdullah Abdullah. India's participation in the talks could only help strengthen those efforts and underscore to the Afghan leaders the importance of a stable and unified Afghanistan, he added.

"My hope is that Pakistan as a country is not isolated by this but is encouraged by this," Kerry said. He said had spoken to Pakistan's Prime Minister Nawaz Sharif about the need for his country to deprive any group of "sanctuary."

"It is vital that Pakistan join with other nations in tackling this challenge, and in fairness in recent weeks and months they have been moving more authoritatively in the western part of the country," Kerry added.

Asked what it will take to re-open talks with Pakistan, Suwaraj said India was not the one creating tensions with Pakistan.

"We told them we want to solve our problems through talks," she said, "But they did things that forced us to suspend the dialogue. The least we expect is there should be action against the perpetrators. Talks can only happen if there is action on their side."

STRONGER TIES

Kerry described the talks with India as "constructive" and said the sides had made headway on a variety of issues, including cyber-security and expanded cooperation on terrorist screening. He said the United States would do more to help upgrade India's power grid and work to provide financing for clean energy projects.

"We are witnessing a moment that defines for certain a very different and renewed relationship between the United States and India," Kerry said.

U.S. Commerce Secretary Penny Pritzker said she would look into India's concerns over an increase in visa fee for professionals that New Delhi has protested, arguing it is a barrier to the movement of workers.

"It is imperative that we look into that issue," Pritzker told the news conference. "The United States recognizes the enormous contribution of foreign workers to our economy, including workers from India."

In March, India filed a complaint with the World Trade Organization, protesting the doubling of the fees for H-1B and L-1 work visas and limits on their numbers.

Earlier, Swaraj said she hoped the next U.S. president would continue the dialogue that also seeks input from companies, which this year included e-commerce giant Amazon and wireless technology firm Qualcomm.

India is keen to attract foreign investment to back Prime Minister Narendra Modi's "Make in India" initiative. Foreign investors want reassurance that Asia's third-largest economy is becoming an easier place to do business.

(Editing by Douglas Busvine and Simon Cameron-Moore, Larry King.)