Tests have confirmed the presence of Ibuprofen in a swab taken from Signoff after his win in the Lord Stakes.

Trainer Darren Weir was told last month the post-race sample from Boxing Day showed an irregularity and further tests confirmed the presence of the prohibited substance.

Signoff is one of several horses treated at a Victorian property for tendon injuries to test positive months after their rehabilitation and despite negative results in other samples.

Weir scratched Signoff from a race last Saturday and gave him a hard gallop instead with tests taken after the work-out.

The results of those samples are expected on Thursday.

Racing Victoria stewards are continuing investigations into the erratic results.