Sonia O'Sullivan has withdrawn from next Saturday's Balmoral international road races in Scotland because of continuing ill health. The chest infection which caused her to drop out of the World Cross Country championships in Belgium a fortnight ago has failed to clear up and she has now started a second course of antibiotics.

The decision to try and compete despite the infection appears to have backfired. O'Sullivan has been unable to train since returning to her London base and her participation in the early part of the track season is now under threat.

O'Sullivan was due to have raced in the South of England road relays at Milton Keynes on Saturday as a warm-up for next week's five miles in Scotland, where England's Paula Radcliffe and Gete Wami of Ethiopia are set to renew their rivalry.

On the advice of coach Alan Storey, it will now be a number of weeks before she is racing again. "Sonia's simply not very well," said Storey. "If she's going to go through these sort of traumas, now is as good a time as any, with the cross-country season and the indoor season over.

"We will be more concerned, obviously, with every week that passes if Sonia has not been able to get back to proper training."

Gary Thornton of NUI Galway was a convincing winner of the IUAA Inter-varsity crosscounty championships in Belfield on Saturday. Thornton finished half a minute clear of second-placed Vincent McGuinness of the University of Limerick. Liz Egan led UL to their first team title in the women's race.