The four Arab nations, which also include the United Arab Emirates, Bahrain and Egypt, accuse Qatar of supporting extremism, a charge which it denies.

They gave the isolated emirate an extra 48 hours to meet their ultimatum after an initial 10-day deadline passed on Sunday.

Saudi Arabia said early Wednesday the four had received Qatar's response and that they would respond "at the right time".

Foreign ministers from the four countries that broke off diplomatic and trade relations with Qatar are due to meet in Cairo from 1100 GMT on Wednesday. A press conference is expected afterwards.

Qatari Foreign Minister Sheikh Mohammed bin Abdulrahman Al-Thani handed an official response on Monday to Kuwait, which is mediating in the dispute, but its contents have not been disclosed.

On Tuesday Qatari Emir Sheikh Tamim bin Hamad Al-Thani received a written reply from Kuwait's Emir Sheikh Sabah al-Ahmad Al-Sabah, the official Qatar News Agency reported.

Doha has said it will not bow to pressure and that the demands seem designed to be rejected.

Sheikh Mohammed told a press conference on Tuesday that the list of demands from the four countries "is unrealistic and is not actionable".

"It's not about terrorism, it's talking about shutting down the freedom of speech," he said.

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.