Saudi Arabia, Bahrain, Egypt and the United Arab Emirates have added 18 individuals and groups to its "terror list", according to state-run Saudi Press Agency (SPA).

The four Arab states cut ties with Qatar on June 5. In addition to placing a political and economic blockade, the countries placed 71 Qatar-funded or Qatar-based individuals and organisations on a ban list because of alleged links to Qatar over "terrorism".

The new entrants include entities from Libya and Yemen and individuals from Qatar, Yemen and Kuwait who the Arab states say have direct and indirect links to Qatari authorities, a joint statement by the Saudi-led group said, according to SPA.

Qatar has vehemently rejected the group's accusations of funding "terrorism" as baseless.

Tuesday's additions to the list include three organisations based in Yemen and six based in Libya, which the four Arab governments accuse of having ties to al-Qaeda.

They also banned three Qataris, three Yemenis, two Libyans and a Kuwaiti they said were implicated in "fundraising campaign to support [former al-Qaeda affiliated] al-Nusra Front and other terrorist militias in Syria", SPA reported.

The move by the four Arab governments came despite mounting international pressure to compromise in their blockade on Qatar which is in its second month.

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On June 22, the Saudi-led group issued a 13-point list of demands, including shutting down Al Jazeera, limiting ties with Iran and expelling Turkish troops stationed in the country, as a prerequisite to lifting the sanctions.

Doha refused to accept those demands.

Earlier this month, Qatar and the US signed an agreement to help combat "terrorism financing".

But the Saudi-led group called the agreement "insufficient" and said it would "carefully monitor the seriousness of Qatari authorities in combating all forms of financing, supporting and harbouring terrorism".

The US has praised Qatar for signing the deal and for its commitment to the effort to "track down and disable terror financing".