Authorities say Cyclone Mekunu killed at least 30 people when it barreled across Oman and Yemen last month.
The International Federation of the Red Cross and Red Crescent Societies said in a statement that the majority of the fatalities happened on the Yemeni island of Socotra, where 20 were killed.
The federation said in a statement Thursday another four were killed in Yemen's al-Mahrah governorate, which borders Oman.
In Oman, authorities had previously said at least six people were killed by the storm.
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Cyclone Mekunu hit Socotra on May 24 before making made landfall on the Arabian Peninsula, about 380 kilometres to the north of the island, early on May 26.
The cyclone caused widespread damage, bringing heavy rains and maximum sustained winds of 170-180kph, with gusts of up to 200kph.