The United Nations has urged India and Pakistan to exercise “maximum restraint” after they ramped up a tit-for-tat diplomatic offensive following a deadly attack on tourists in Indian-controlled Kashmir.

An attack on tourists in India's Himalayan territory of Kashmir this week sparked a new crisis between nuclear armed South Asian neighbours India and Pakistan, with New Delhi blaming militants with "cross-border linkages" for the killings.

Following the recent terror attack in Pahalgam, Pakistan has closed its airspace to Indian airlines, leading to longer flight times and potential fare increases for international routes from Delhi and other northern cities.