WASHINGTON • The United States threw its support behind India on Tuesday and pressed Pakistan to punish those behind a suicide attack in Kashmir that killed more than 40 Indian security troops.

This comes after United Nations Secretary-General Antonio Guterres called on India and Pakistan to take immediate steps to defuse tensions and offered to help broker a solution if both sides agreed.

US State Department deputy spokesman Robert Palladino told reporters: "We have been in close communication with the government of India to express not only our condolences but our strong support for India as it confronts this terrorism."

He added: "We urge Pakistan to fully cooperate with the investigation into the attack and to punish anyone responsible."

Mr Palladino said the US has been in contact with both countries since a suicide attack on Feb 14 in Kashmir killed more than 40 Indian security forces, triggering counter-operations by Indian forces in the area.

The attack was claimed by the Pakistan-based Islamist group Jaish-e-Mohammad (JeM).

"We call on all countries to uphold their responsibilities pursuant to the United Nations Security Council resolutions to deny safe haven and support for terrorists," Mr Palladino said.

UN spokesman Stephane Dujarric, meanwhile, said the UN is "deeply concerned" at the increasing tensions between both India and Pakistan.

Mr Guterres "stresses the importance of both sides to exercise maximum restraint and take immediate steps" to de-escalate, while also offering to mediate "should both sides ask", said Mr Dujarric.

Pakistani Foreign Minister Shah Mehmood Qureshi appealed to Mr Guterres to step in to defuse tensions in a letter seen by Agence France-Presse.

"It is imperative to take steps for de-escalation. The United Nations must step in to defuse tensions," said the letter sent on Monday.

Although the attack was claimed by JeM, Mr Qureshi insisted that "attributing it to Pakistan even before investigations is absurd".

In response to the rising tensions, France, Britain and the US were considering a new push at the Security Council to place JeM leader Masood Azhar on the UN terror list, but faced opposition from China, diplomats said.

China has twice blocked - in 2016 and 2017 - attempts to put the JeM leader on the blacklist.

The group itself was added to the terror list in 2001.

Kashmir has been split between India and Pakistan since independence from Britain in 1947.

Both countries claim the former Himalayan kingdom in full and have fought two wars over it.

India has long accused Pakistan of harbouring militants who launch attacks on its soil.

Pakistan's UN Ambassador, Ms Maleeha Lodhi, met Mr Guterres and the president of the Security Council to appeal for action, warning that a flare-up in Kashmir could undermine peace efforts in Afghanistan.

"The escalation in the subcontinent poses a threat to prospects for peace in Afghanistan," Ms Lodhi told AFP.

AGENCE FRANCE-PRESSE