Prof Ian Temperley clashed with the Irish Blood Transfusion Service over claims the agency played a mere "warehousing" role in the supply of blood products to patients.
He said he did not agree with the opinion of Dr Emer Lawlor, the IBTS's deputy medical director, that responsibility for product selection rested solely with treating doctors.
He said he presumed no reputable company or organisation would sell something which it did not think was satisfactory. The Blood Transfusion Service Board, as the IBTS was formerly known, "of course" had a responsibility, said Prof Temperley.
He doubted he would have changed the product he used without reference to the blood bank.
The doctor was being crossexamined by counsel for the Irish Haemophilia Society, Mr Martin Hayden, on the third phase of the inquiry - that dealing primarily with the response of treating doctors to the infection of haemophiliacs with HIV and hepatitis C.
In a separate development, Prof Temperley confirmed Dr Lawlor was the senior doctor responsible for instructing that a commercial concentrate be given to Mr John Berry, a mild haemophiliac, in 1979 when a shortage of sterile water made it impossible to administer a safer, locally made product.
Mr Berry, a father of three from Athy, Co Kildare, was infected with hepatitis C through the commercial product and has since died.
The tribunal heard two weeks ago that Mr Berry developed a nosebleed at St James's Hospital on the morning of January 9th, 1979.
Hospital records show he was due to have been treated with locally made cryoprecipitate but there was insufficient sterile water available to prepare the product.
The junior doctor on duty consulted Dr Lawlor who, it was confirmed yesterday, gave permission for commercial factor 8 to be used instead.
Prof Temperley said it was "peculiar" that no sterile water was available, although "it was not a common fluid" in the wards. Medical staff may have had to go to the pharmacy or laboratory to locate some, he said.
Earlier, Prof Temperley was questioned about a retrospective study of severe haemophilia A patients infected with HIV.
It suggested that of 23 haemophiliacs tested for the virus from an early period, 17 - or three-quarters - were positive by 1983 while the remainder became infected between then and 1985.
Prof Temperley agreed the patients in question would have had the greatest exposure to commercial concentrates and, therefore, would have been the most likely cohort to first develop problems regarding HIV infection.
He refused to be drawn, however, on whether he agreed or disagreed with Dr Lawlor's conviction that 95 per cent of haemophiliacs were infected by 1983.
He stressed the figures were open to interpretation and he did not wish to comment further on Dr Lawlor's view on the subject, with which, he said, he was familiar.
He noted, however, that he did not know the exact means of her analysis and "she and I have arguments about this too".
