NEW DELHI/ISLAMABAD (Reuters) -- India has warned its citizens it was unsafe to travel to Pakistan and the prime minister met his military chiefs, while Pakistan canceled army leave and moved some troops from its western border.
The travel warning marked a dramatic rise in tension between the nuclear-armed neighbors after last month's attack on Mumbai that killed 179 people and which India has blamed on Islamist militants based in Pakistan.
It followed media reports in Pakistan and India that "several" Indian nationals had been held in the last two days after bombings in the Pakistani cities of Lahore and Multan.
"Indian citizens are therefore advised that it would be unsafe for them to travel [to] or be in Pakistan," India's Foreign Ministry spokesman said in a statement.
Another Foreign Ministry official contacted by Reuters said the warning referred to all travel to Pakistan.
Prime Minister Manmohan Singh had earlier discussed tension with Pakistan during a scheduled meeting about military pay with the chiefs of the army, navy, and air force, his office said.
"The prime minister met the tri-services chiefs to discuss the pay commission issues but obviously the situation in the region was also discussed," said an official from Singh's office, who requested anonymity. There were no other details.
Indian media said national security adviser M.K. Narayanan also attended the meeting.
Many analysts say it is very unlikely that the tension will descend into war. The uneasy neighbors have fought three wars since independence in 1947 and came to the brink of a fourth in 2002 after an attack on the Indian parliament.
"We hope that both sides will avoid taking steps that will unnecessarily raise tensions during these already tense times," U.S. National Security Council spokesman Gordon Johndroe told reporters in Washington.
While there had been no significant troop movements in either India or Pakistan, military officials in Islamabad said army personnel had been ordered to report to barracks and some troops had been moved off the Afghan border.
"A limited number of troops from snow-bound areas and areas where operations are not being conducted have been pulled out," said a senior security official who declined to be identified.
The official declined to say where the troops had been moved to, citing the sensitivity of the issue, but Pakistani media have reported some troops had been redeployed to the Indian border.
A senior police official in Pakistan's Punjab Province denied that any Indians had been arrested over the Lahore and Multan blasts but an intelligence agency official, who declined to be identified, said an Indian had been detained on December 24.
Several more Indians had been detained based on information obtained from that suspect, the intelligence official said.