China has stonewalled India's request to blacklist Jaish-e-Mohammad chief Maulana Masood Azhar, New Delhi said, in a move that could ratchet up tensions between the two countries.
India has been pushing to include the Jaish leader's name in the UN Security Council blacklist of groups linked to al Qaeda.
New Delhi believes Azhar orchestrated a deadly attack on an Indian air base in January.
China had previously put a 'technical hold' on the move in April.
While Jaish-e-Mohammad has been blacklisted by the UN Security Council, its chief is yet to be red-flagged.
"We had expected China would have been more understanding of the danger posed to all by terrorism," Indian foreign ministry spokesman Vikas Swarup said in a statement.
Swarup added that the inability of the international community to take the step showed the "prevalence of double standards in the fight against terrorism".
The spokesperson added that New Delhi was surprised by Beijing's decision.
China's foreign ministry did not immediately respond to a request for comment late on Friday evening.
China had two options in front of them -- either to prolong the "hold", which would mean that Azhar would be banned due to activation of UNSC's resolution 1267, or "block" India's effort.
India has long accused its neighbour Pakistan of using Jaish-e-Mohammad as a front to mount attacks on Indian soil, including in the disputed Kashmir region. Pakistan, however, denies giving any aid to Kashmir-based militants.
If Azhar was blacklisted by the UN Security Council, he would face a global travel ban and asset freeze.