A key South Asian summit was in doubt on Wednesday after India and three other countries pulled out following a deadly attack on an army base that New Delhi blames on a Pakistan-based group.
India has sought to isolate Pakistan in the wake of the raid on its base in the disputed region of Kashmir, which killed 18 soldiers and triggered public fury.
On Tuesday it said Prime Minister Narendra Modi would not attend the South Asian Association for Regional Cooperation (SAARC) summit in Islamabad in November, in a major snub to its neighbour.
In Islamabad, a senior Pakistani foreign ministry official who declined to be identified said the meeting would be postponed following the four withdrawals.
Without naming Pakistan, India's foreign ministry said "increasing cross-border terrorist attacks in the region and growing interference in the internal affairs of member states by one country" had created an environment that was not conducive for a meeting.
Hours later, Bangladesh said it was also pulling out. Afghanistan and Bhutan -- both close India allies -- have since followed suit, according to an official with the Nepali government, current chair of SAARC.
"Pakistan has been interfering in our internal affairs for some time," a senior Bangladesh foreign ministry official told AFP, requesting anonymity.
"That's why we have pulled out of the SAARC summit."
Under pressure to act after the Kashmir raid, Modi warned Pakistan in a major speech on Saturday that India would push to make it a pariah state.
Pakistan denies any involvement in the September 18 attack, the worst of its kind in over a decade.
But India's army has blamed Jaish-e-Mohammad, a Pakistan-based militant group that was also implicated in an audacious assault on an Indian air force base in the northern town of Pathankot in January.
At the last SAARC summit in 2014 a newly-elected Modi shook hands with his Pakistani counterpart Nawaz Sharif, raising hopes of warmer ties.
Just over a year later Modi made a surprise Christmas Day visit to Pakistan for a meeting with Sharif.
But those hopes were dashed by the Pathankot attack in which seven Indian soldiers died, and peace talks have been on ice ever since.
'Closer to China' 
Current SAARC chair Nepal said it hoped the issues would be resolved but could not comment on whether the summit would go ahead.
"The host will take decisions regarding the summit," said Jhabindra Aryal, joint secretary with Nepal's foreign ministry.
The foreign ministry official in Islamabad, speaking on condition of anonymity, said SAARC officials "will reorganise future dates for the conference". A formal announcement postponing the summit "has to come from the SAARC secretariat and not from us", the official said.
The leaders of the eight SAARC countries -- which also include Sri Lanka, Nepal and the Maldives -- expressed frustration after the last summit in Kathmandu with the slow pace of progress towards greater regional integration.
Analysts say this is due to the mutual mistrust between Pakistan and powerhouse India.
Cyril Almeida, a columnist in Pakistan's English-language daily Dawn, said India's move to exclude Pakistan from regional discussions was not unexpected.
"Diplomatically, (it's) maybe not a big deal for Pakistan given that SAARC is widely perceived as ineffective," he said.
"But (it's) a fresh sign of Pakistan not being in a comfortable place in its own region."
Analyst Ashok Malik said the withdrawals would have little practical impact on Pakistan.
"It basically scores a symbolic and a political victory. As for Pakistan, this will push it even closer to China," said Malik, head of the Delhi-based Observer Research Foundation's regional studies initiative.
Pakistan said it remained "committed to peace and regional cooperation" and accused India of perpetrating "terrorism" on its soil.
"As for the excuse used by India, the world knows that it is India that has been perpetrating and financing terrorism in Pakistan," tweeted foreign ministry spokesman Nafees Zakariya late on Tuesday, citing the capture of an Indian intelligence officer in Balochistan earlier this year.
Pakistan has repeatedly accused India of interference in the southwestern province, which borders Iran and Afghanistan and is afflicted by Islamist militancy and a separatist insurgency.