ISLAMABAD (REUTERS) - Pakistan has told both Indian journalists stationed in Islamabad to leave within a week, the two said on Wednesday, and New Delhi criticised this as a retrograde step that would weigh on confidence-building measures between the nuclear-armed rivals.

Tensions are simmering between Pakistan's powerful military and a civilian government that appears dovish towards neighbouring India, where Hindu nationalist opposition leader Narendra Modi appears set to win a general election.

Late on Tuesday night, Snehesh Alex Philip of The Press Trust of India and Meena Menon of The Hindu received letters telling them that their visas would not be renewed, the journalists told Reuters on Wednesday.

They said no reason was given. Both had been in Pakistan for less than a year.

"It is regrettable and unfortunate that the two Indian correspondents in Pakistan have been asked to leave prematurely and suddenly only a few months after their arrival there,"Indian Foreign Ministry spokesman Syed Akbaruddin said.

Pakistani authorities did not return calls seeking comment.

Pakistan has become an increasingly dangerous place for journalists to operate, but restrictions put on the movements of Indian reporters are stricter than those applied to other foreign journalists.

Prime Minister Nawaz Sharif has repeatedly said publicly that he wants to improve relations with India and has pledged to improve press freedoms. But Pakistan's military remains deeply suspicious of both journalists and India.

Pakistan and India have fought three wars since they became separate countries on independence from Britain in 1947. Their governments have a reciprocal dealt allowing two correspondents from each country to be stationed in the other's capital.

Pakistani journalists face much greater threats than foreigners, however. At least 34 Pakistani journalists have been killed for their work since Pakistan returned to democracy in 2008, but in only one case has the killer been convicted.

Pakistan's feared military spy agency has been implicated in numerous cases of abductions, torture, and killings, an Amnesty International report said last month.

The defence ministry demanded in April that Geo TV, the country's most popular channel, be shut down after it aired accusations that the spy agency was responsible for the shooting of one of its top news anchors.

Last year, the Islamabad government expelled a reporter from The New York Times.