USDAW representative Dave Williams said: "The situation is we don’t have an agreement with Homebase over head office staff. We have a handful of members there are we will provide support but we are not part of the consultation on any job losses. It’s a bit out of our control. No-one has contacted us."
Wesfarmers results are due on Thursday.
Williams added that USDAW has an agreement with Tesco but does not represent Dobbies. Dobbies is for sale and has received a bid from Wyevale Garden Centres owner Terra Firma.
Quick cost savings for Wyevale if it bought Dobbies could be to close the Edinburgh head office of the 36-centre company and cut head office staff to avoid duplication.