DUBAI (Reuters) - Four Arab countries have added 18 more groups and individuals that they say are linked to Qatar to their “terrorist” lists, Saudi state news agency SPA reported on Tuesday, further escalating a row with Doha that has stoked regional tensions.

FILE PHOTO: Flags of Arab states are seen along the Nile river ahead of a meeting of the foreign ministers of Egypt, Saudi Arabia, UAE, and Bahrain, in Cairo, Egypt July 5, 2017. REUTERS/Mohamed Abd El Ghany

The lists now include three Yemeni charities, three Libyan media outlets, two armed groups and a religious foundation, some of which are already subject to U.S. sanctions.

“The terrorist activities of the aforementioned entities and individuals have direct and indirect ties with the Qatari authorities,” a statement issued by Saudi Arabia, Egypt, the United Arab Emirates and Bahrain said.

The four states cut ties with Qatar - a major global gas supplier and host to the biggest U.S. military base in the Middle East - on June 5, accusing it of financing militant groups in Syria, and allying with Iran, their regional foe.

The row erupted following remarks attributed to Qatar’s emir, Sheikh Tamim bin Hamad al-Thani, in which he was quoted as praising Gaza’s ruling Islamist Hamas movement and calling Iran an “Islamic power” on May 23. Qatar said the emir did not make the remarks and the agency’s website had been hacked.

Qatar has not yet commented on Tuesday’s updated list, but last month it denied the allegations and dismissed charges of support for Islamist militancy, calling them “baseless allegations that hold no foundation in fact”.

Qatar’s foreign minister, in comments to Doha-based channel Al Jazeera late on Tuesday, did not directly refer to the new list but criticized the four countries for actions which he said were undermining mediation efforts backed by the United States.

“We see there is a negative behavior aimed at influencing the mediation, either through statements or through (media) leaks which they launch at critical moments,” Sheikh Mohammed bin Abdulrahman al-Thani said.

He reiterated the Qatari position that Doha was ready for dialogue on a range of issues of concern but that it would not negotiate over topics to do with internal affairs and that the boycott against it must be lifted.

Mediation efforts led by Kuwait and shuttle diplomacy by Western officials, including U.S. Secretary of State Rex Tillerson and Turkey’s President Tayyip Erdogan have failed to end what has become the worst rift between Gulf Arab states in years.

Tuesday’s statement accused Qatari, Kuwaiti and Yemeni nationals of helping to raise funds for al Qaeda. The statement also said that two Libyan individuals and six groups were suspected of being affiliated with “terrorist groups in Libya”.

The groups include two television stations, one of which is affiliated with the Qatar-based Al Jazeera television, a militia group based in the eastern Libyan city of Benghazi and one of its senior commanders.

“They have received substantial financial support from the Qatari authorities and played an active role in spreading chaos and devastation in Libya,” the statement said.