LONDON

Britain issued a travel advisory for its citizens Thursday, advising them not to travel within 10 kilometers (6.2 miles) of India and Pakistan's border areas due to rising tensions between the two nuclear neighbors.

In its update, the Foreign Office said all travel within 10 kilometers (6.2 miles) of the India-Pakistan border must be avoided because the Wagah-Attari border has been closed.

It added: "FCDO advises against all travel to the region of Jammu and Kashmir (including Pahalgam, Gulmarg, Sonamarg, the city of Srinagar and the Jammu-Srinagar national highway) except for travel by air to and from the city of Jammu, travel within the city of Jammu, travel within the Union Territory of Ladakh."

In addition, the Foreign Office advised British citizens to avoid all but essential travel to the northeastern Indian state of Manipur, including its capital, Imphal.

The UK issued a travel advisory two days after unidentified gunmen killed 26 people, including 25 tourists, mostly Indians, and one local resident, in Pahalgam in Indian-administered Kashmir on Tuesday.

India announced it has suspended the bilateral Indus Water Treaty, closing the border crossing with Pakistan.

New Delhi also declared Islamabad's defense/military, naval, and air advisors persona non grata at the Pakistani High Commission in New Delhi, giving them one week to leave the country.

The move, called by Islamabad "reckless," warned that any attempt by India to divert or stop water to Pakistan would be considered an "act of war."

Early Thursday, India asked its citizens visiting Pakistan to return home "at the earliest."