Queen Elizabeth Stakes-winning trainer Kris Lees will face a positive swab inquiry, a Racing NSW stewards' statement has confirmed.

The Lees-trained City Of Justice tested positive to the anti-inflammatory drug ibuprofen after winning at Taree in January.

Newcastle-based Lees will front stewards on May 9, less than a month after he trained Lucia Valentina to win Sydney's richest race, the $4 million Queen Elizabeth Stakes at Randwick.

Wyong trainer Stephen Farley has been called to an inquiry a day following Lees' hearing after his horse Di's Diamond returned an elevated cobalt level.

Di's Diamond tested positive after finishing unplaced in a race for three-year-olds at Taree in February.

An inquiry into two elevated cobalt readings from Alma's Fury following the Apollo Stakes and Doncaster Prelude in 2013 will resume on May 16 with the hearing of eight charges against trainer Paul Murray.