AN official in Cyprus says aid ships that arrived in Gaza this week will return to the Mediterranean island nation carrying some 240 tons of undelivered aid after an air strike killed seven aid workers.

Foreign Ministry spokesman Theodoros Gotsis said that around 100 tons of aid had been unloaded before World Central Kitchen (WCK), an international charity, suspended operations.

Seven of the charity’s workers were killed by an apparent Israeli strike.

The UK's Foreign Secretary says British nationals are reported to have been killed. An Australian, Polish, Palestinian, and a dual US-Canadian citizen have also died, WCK said.

The CEO of WCK says it was an "unforgiveable attack". 

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Cyprus has played a key role in trying to establish a maritime aid corridor to Gaza from its port city of Larnaca.

Those efforts suffered a major setback when WCK halted operations.

Cyprus’ Foreign Minister Constantinos Kombos said the charity is suspending operations in Gaza out of respect for the victims as well as to review security protocols.

Israel has expressed sorrow over the deaths and vowed to carry out an independent investigation into what happened while stopping short of accepting responsibility.