Given the following context:

During the day, the Foreign Office held further talks with diplomats from Arabian countries in the hope of persuading them to go to the embassy and talk to the hostage-takers. The talks, hosted by Douglas Hurd, ended in stalemate. The diplomats insisted they must be able to offer safe passage out of the UK for the gunmen, believing this to be the only way to guarantee a peaceful outcome, but the British government was adamant that safe passage would not be considered under any circumstances. Karkhouti, through whom Oan had issued his revised demands the previous day, became increasingly ill throughout the day and by the evening was feverish, which led to suggestions that the police had spiked the food that had been sent into the embassy. John Dellow, the commander of the police operation, had apparently considered the idea and even consulted a doctor about its viability, but eventually dismissed it as "impracticable".The SAS officers involved in the operation, including Brigadier Peter de la Billière, Director Special Forces, Lieutenant-Colonel Rose, Commander of 22 SAS, and Major Hector Gullan, commander of the team that would undertake any raid, spent the day refining their plans for an assault.

answer the following question:

What person issued demands through the man who became ill and feverish? 

Oan