Germany's foreign minister said he no longer sees the risk of military escalation in the Gulf standoff, despite an angry reaction from four Arab nations to Qatar's response to the crisis.

Saudi Arabia, Egypt, the United Arab Emirates and Bahrain, who have have imposed a blockade on Qatar for its alleged support for terrorism, issued a statement in Cairo on Wednesday, saying that Doha's response to their demands to end the crisis was "not serious".

Foreign Minister Sigmar Gabriel said that, while the reaction sounded harsh, many demands that were initially made were no longer mentioned.

Gabriel visited Saudi Arabia, Qatar and mediator Kuwait this week as the Saudis and others seek to isolate Qatar over its alleged support for extremists.

READ MORE: All the latest updates on the Qatar-Gulf crisis

He said Germany's intelligence service would participate in efforts to clear up the accusations by Qatar's neighbours.

Gabriel told Deutschlandfunk radio on Thursday that there was an agreement for Qatar to "open all its books" to Germany's intelligence service "if we have questions about certain people or structures".

Saudi Arabia, the United Arab Emirates, Bahrain and  Egypt announced on June 5 they were severing ties with Qatar for supporting "terrorism" and later put forward a list of 13 demands. Qatar denies the allegations.

'Isolation, incremental measures'

Saudi Foreign Minister Adel al-Jubeir said at the news conference in the Egyptian capital that "the boycott [against Qatar] will remain".

The four Arab states stopped short of announcing new sanctions but Jubeir said they would "take steps at the appropriate time".

The UAE state minister for foreign affairs, Anwar Gargash, on Twitter predicted more isolation for Qatar.

The demands include Doha ending support for the Muslim Brotherhood and closing Al Jazeera.

Saudi Arabia and its allies have not said what steps they could take next, but there are fears of a wider embargo that would hurt the Qatari economy. Credit ratings agency Moody's announced it was changing Qatar's outlook to negative over the crisis.

Al Jazeera's Marwan Bishara analyses the Saudi-led Gulf blockade

Source: Al Jazeera and news agencies