It is believed Mowbray has met chief executive Peter Lawwell at the Hoops' Lennoxtown training ground, although the club have so far refused to officially confirm or deny their manager's departure.
The humiliating defeat to St Mirren has left Celtic ten points behind Rangers, who also have two games in hand and it is believed the board have acted.
Mowbray only joined Celtic in the summer, when he was also tipped to succeed Gareth Southgate at the Riverside Stadium.
It is also expected that Mowbray's long-term assistant Mark Venus, from Hartlepool, has followed him out of Parkhead.
Source: Northern Echo
Source: Northern Echo