Doha: The diplomatic crisis surrounding the Gulf escalated further Friday after Saudi Arabia and its allies placed a number of Qataris and Doha-based organisations on a "terror list".

As many as 18 individuals were named, including members of Qatar`s royal family and a former minister.

Also named were Doha-based Muslim Brotherhood spiritual leader Yusuf al-Qaradawi and Qatari-funded charities.

The list was published jointly by Saudi Arabia, the United Arab Emirates, Egypt and Bahrain -- which accuse Qatar of supporting Islamist extremist groups and have cut ties with Doha.

"This list is connected to Qatar and serves suspicious agendas in an indication of the duality of Qatar policies," said the statement.

It shows that Qatar "announces fighting terrorism on one hand and finances and supports and hosts different terrorist organisations on the other hand".

In all, 59 people and entities were listed.

It was released hours after Qatar`s Foreign Minister Sheikh Mohammed bin Abdulrahman Al-Thani said Doha would not "surrender" and rejected any interference in its foreign policy.

Qatar said the blacklist had no basis in reality.

"The recent joint statement issued by the Kingdom of Saudi Arabia, Bahrain, Egypt and the UAE regarding a `terror finance watch list` once again reinforces baseless allegations that hold no foundation in fact," a government statement read.

"Our position on countering terrorism is stronger than many of the signatories of the joint statement -- a fact that has been conveniently ignored by the authors."

It added: "We lead the region in attacking the roots of terrorism."Friday`s spat is unlikely to ease regional tensions in a spiralling political crisis which also threatens to involve the US, Russia, Europe and other major players such as Turkey and Iran.

Turkey`s parliament has approved deploying troops to a base in Qatar and Iran has offered to send food to Doha.

On Monday, Saudi Arabia, the UAE, Egypt and Bahrain led a string of countries that cut ties with Qatar over what they say is the emirate`s financing of extremist groups and its ties to Iran, Saudi Arabia`s regional arch-rival.

They also banned Qatar Airways from their airspace and closed Qatar`s only land border with Saudi Arabia, moves Doha`s foreign minister termed a "blockade".

On Friday, Sheikh Mohammed held surprise talks in Germany with his counterpart Sigmar Gabriel.

In a press conference, he claimed the actions by the Gulf states were "a clear breach of international law".

Denouncing the blacklist, he added: "There is a continuous escalation from these countries... but our strategic options are still diplomacy and dialogue."

Gabriel stressed that "this is the hour of diplomacy".

So far, European countries have largely stayed on the sidelines in the dispute.

Sheikh Mohammed is expected in Moscow Saturday, and officials said Friday he spoke with US Secretary of State Rex Tillerson by telephone.The blacklist is the latest allegation by Saudi Arabia and its allies against Qatar since the crisis erupted late last month.

The Arab states have also ordered Qataris out within 14 days.

Qatar`s national human rights committee said families had been split and hundreds of people affected.

The feud has raised fears of wider instability in an already volatile region that is a crucial global energy supplier and home to several Western military bases.

Kuwait -- which unlike most of its fellow Gulf Cooperation Council (GCC) members has not cut ties with Qatar -- has led mediation efforts.

US President Donald Trump, who had initially backed the measures against Qatar in a tweet, called Sheik Tamim on Wednesday with an offer "to help the parties resolve their differences".

Qatar hosts the Al-Udeid military base, the largest US airbase in the Middle East that is central to the fight against the Islamic State group in Iraq and Syria.

Questions have also been raised over whether Qatar should retain the right to host the 2022 football World Cup and over its economic ability to sustain the crisis.

Qatar is the world`s largest exporter of Liquid Natural Gas, but industry experts say shipowners are seeking clarity on the UAE`s ban on Qatari-linked vessels calling at its ports.

"The ban will certainly have an impact on cargo contracts... where Qatar is a source or destination," said Singapore-based shipping lawyer K Murali Pany.Analysts say the crisis is partly an extension of a 2014 dispute, when Saudi Arabia, the UAE and Bahrain temporarily recalled their ambassadors over Qatari support for Egypt`s Muslim Brotherhood.

A top Gulf official, on condition of anonymity, told AFP that a major concern was the influence of Sheikh Tamim`s father Sheikh Hamad, who had allowed the Taliban to open an office in Doha and helped arm Syrian rebels before abdicating in 2013.

Doha has for years forged its own alliances in the region, often diverging from GCC policies and taking in leaders of the Muslim Brotherhood, the Palestinian Hamas and members of the Afghan Taliban.