Qatar on Monday responded to a list of demands from Saudi Arabia and its allies after they agreed to give a defiant Doha another 48 hours to address their grievances.

Details of the response were not immediately available, but a Gulf official told AFP that Qatari Foreign Minister Sheikh Mohammed bin Abdulrahman Al-Thani had delivered it during a short visit to Kuwait, which is acting as a mediator in the crisis.

Saudi Arabia, the United Arab Emirates, Bahrain and Egypt had announced in the early hours of Monday they were pushing back a deadline for Qatar to agree to a list of 13 demands they issued on June 22.

A joint statement said they were extending the ultimatum, which had been due to expire at the end of the day on Sunday, at the request of Kuwait's emir.

The demands included Doha ending support for the Muslim Brotherhood, closing broadcaster Al-Jazeera, downgrading diplomatic ties with Iran and shutting down a Turkish military base in the emirate.

Sheikh Mohammed had earlier said the list of demands was "made to be rejected".

Saudi Arabia and its allies announced on June 5 they were severing ties with their Gulf neighbour, sparking the worst diplomatic crisis to hit the region in decades.

They accused Qatar of supporting extremism and of being too close to Saudi Arabia's regional arch-rival Iran, which Doha has strongly denied.

The crisis has raised concerns of growing instability in the region, home to some of the world's largest energy exporters and several key Western allies who host US military bases.

German Foreign Minister Sigmar Gabriel, who on Monday starts a tour of several Gulf states, called for "serious dialogue" to end the crisis.

"We are worried that the distrust and the disunity could weaken all the parties concerned as well as the entire peninsula," said Gabriel, who will visit Saudi Arabia, the United Arab Emirates and Qatar.