Scottish Labour is accused of failing to act over harassment allegations against Alex Rowley, after it emerged that the party was made aware of the claims five weeks ago.

The party suspended Rowley on Wednesday evening. He had already stepped aside as interim leader earlier that day after a former partner accused him of stalking and harassment following the breakdown of their relationship.

The claims, which appeared in Wednesday’s Scottish Sun, included the allegation that the MSP for Mid Scotland and Fife had sent a series of abusive text messages to the woman, who described him as “a ruthless bully” who had harassed her for three years following the end of their relationship.

Rowley denies the claims, and has insisted he will “take all steps” to clear his name.

It has now emerged that journalists contacted Scottish Labour about the allegations on 10 October, five weeks before they eventually appeared in print, but received letters from lawyers acting on behalf of Rowley which warned against publication.

The party insists that it was not presented with sufficient information or evidence to warrant an investigation of Rowley at that time.

A spokesperson said: “The party had insufficient knowledge to initiate any type of formal investigation prior to the reports being featured in the Sun newspaper.

“The party has acted in accordance with procedures at all times. No complaints were received or evidence shared with the party prior to reports in the Sun newspaper.”

The party was also asked by the Guardian three weeks ago, on 30 October, if it had “investigated or received any allegations that its MSPs and/or staff have been the perpetrators or subjects of unwanted sexual approaches; lewd or sexist behaviour or of sexual harassment”.

A Scottish Labour press officer replied categorically: “No, we have not,” a response which now appears to be incomplete.

Following the revelations on Wednesday morning, Rowley immediately stepped aside as interim leader, but the party did not suspend him. By Wednesday afternoon, both candidates for the role of Scottish Labour leader, Anas Sarwar and Richard Leonard, as well as the party’s previous leader, Kezia Dugdale, had called for Rowley to be suspended.

At the end of what has often been an ill-tempered leadership contest between Sarwar and his Corbynite challenger Leonard, the results of which will be announced on Saturday, both men pledged “a zero-tolerance approach” to sexual harassment if they were elected leader.

Rowley, who previously worked as an education official for the TUC, acted as election agent for the former prime minister Gordon Brown for five years.