The Pakistani Taliban have declared allegiance to IS militants in Syria and Iraq.
In a statement, the group appealed for unity against the “enemy” - the US-led alliance, saying it fully supports IS goals.
The IS, which controls swathes of land in Syria and Iraq, has been making inroads into South Asia, which has traditionally been dominated by local Taliban insurgencies against both the Pakistan and Afghanistan governments.
The Pakistani Taliban has been waging its own insurgency against the Islamabad government since 1997. Kabul has also been battling the Taliban militancy since the 2001 US invasion of Afghanistan.
The Pakistani Taliban, funded by local as well as foreign charity donations from wealthy supporters in the Persian Gulf and elsewhere, operate separately from the Afghan insurgents of the same name, but are loosely aligned with them.
‘Forget Rivalries’
Saturday’s statement was issued by the leader of Tehreek-e-Taliban Pakistan (TTP), Maulana Fazlullah, sent by his spokesman.
Addressing IS in Syria and Iraq, he said: “We are proud of your conquests against the enemies. We are with you in good and bad times.”
“In these troubled days, we call on you to be patient and stay united as your enemies are now united against you. Forget rivalries.”
Recently, according to BBC, supporters of IS have been spotted in the north-western Pakistani city of Peshawar distributing pamphlets praising the group.
The United States has been carrying out strikes in Iraq against the militant group since July and in Syria since late September with the help of Arab allies. Britain and France have also struck Islamic State targets in Iraq.
On Saturday, Kurdish Peshmerga fighters and Shia militiamen drove IS fighters from a strategically important bridge near the northern city of Kirkuk.
In Syria, IS has been advancing on the town of Kobane, on the Turkish border, which has become a key battleground between the militants and its opponents, who include Kurdish fighters as well.
More than 160,000 Syrians, mainly Kurds, have fled across the border since IS launched its offensive on Kobane last month.
