Saudi Arabia and three other Arab states have extended the deadline for Qatar to accept a list of demands by 48 hours, or face further sanctions.
The initial deadline for Qatar to agree to the group’s 13 demands, including the shutting down of the Al Jazeera news network, expired on Sunday.
The Gulf state, which denies funding extremism, has given a formal response, but details have not been released.
It has already called the demands an “affront to international law”.
The requirements include the closure of a Turkish military base in Qatar and the curbing of diplomatic relations with Iran.
Qatari Foreign Minister Sheikh Mohammed bin Abdul Rahman al-Thani was in Kuwait on Monday to hand over a formal response in the form of a letter from the emir of Qatar to the emir of Kuwait, the main mediator in the Gulf crisis.
In a statement released shortly beforehand, lawyers for Qatar denounced the demands and called for international condemnation.