The French outfit won promotion to Ligue 1 last season and want to reinforce their defensive options as they look to cope with the step up to the top tier.
They are keen on Celtic centre-back Welsh as a potential signing and have been in touch with the Glasgow giants.
And so far Toulouse’s efforts have yet to go beyond putting in an enquiry for Welsh.
It is suggested that Celtic boss Ange Postecoglou wants to keep hold of Welsh as he sees the defender playing a part under him this season.
However, Celtic could have their stance tested if Toulouse choose to translate their interest into a firm bid for Welsh.
Welsh, 22, made a total of 24 appearances across all competitions for Celtic over the course of last season as the Bhoys won the Scottish Premiership and the Scottish League Cup.
The defender still has another three years left to run on his contract at Celtic Park.
