The newly formed National Coalition for Syrian Revolution and Opposition Forces has been rejected by Islamist rebels in the country.
Around 13 organisations were listed in a video released on the internet, denouncing the new group.
"We are the representatives of the fighting formations in Aleppo and we declare our rejection of the conspiratorial project, the so-called national alliance," it says.
"We have unanimously agreed to urgently establish an Islamic state."
The new leader of the opposition, Moaz al-Khatib said they will reach out to the groups.
"We will keep in contact with them for more cooperation in the interest of the Syrian people," he said.
The EU meanwhile has recognised the coalition as the “legitimate representatives of the aspirations of the Syrian people”.
France was one of the first countries to recognise the opposition and said they saw the group as the “sole representative” of Syrians.
Turkey and six Gulf states have also formally recognised the opposition grouping.
