The Scottish Professional Football League has launched a formal investigation into "unacceptable conduct" during Rangers' clash with Hibernian and Hearts' match with Dundee United.

The league body has announced it is looking into incidents following a review of reports from the match delegate.

Rangers condemned supporters who sang sectarian songs, including the banned Billy Boys, during the Scottish Championship match at Ibrox on December 28.

STV understands the league is also looking into reports of disturbances in Tynecastle's Roseburn Stand during Hearts' win over United on December 30.

The news comes after the SPFL revealed plans to introduce facial recognition technology at Scottish grounds in a bid to identify known troublemakers.

Punishments for clubs who fail to prevent offensive behaviour would be increased as part of the new initiative.

League representatives have already met the Scottish Government to discuss possible public funding for the proposals, which could cost up to £4m

An SPFL spokesman said: “The SPFL is committed to addressing unacceptable conduct where it occurs.”

Last August, the league charged Motherwell over crowd trouble at the end of the Premiership Play-Off final against Rangers.

A commission chaired by an independent senior solicitor was to hear the case but no verdict has yet been released.