Pugh died on Thursday night after a long battle against illness during which he had a cancerous tumour removed from one of his kidneys last September.
The Cardiff-based QC was hugely influential in rugby's development as a professional game and kept close links with Welsh rugby after his elevation to the world stage.
Pugh was poached by the IRB from the Welsh Rugby Union to take up his post as the board's first ever independent chairman.
Under Pugh, the sport became more professional from grass-roots level upwards. He was instrumental in bringing Italy into the Six Nations championship and also helped set up the Heineken Cup.
Due to his ongoing illness, Pugh had not worked full-time for the IRB for the last nine months with vice-chairman Syd Millar stepping up as acting chairman during this period.
