Two men have been arrested in connection with an investigation into parcel bombs sent to Celtic manager Neil Lennon and to two high-profile supporters of the club.
The men, aged 41 and 43, were detained after officers raided a number of properties in Kilwinning, Ayrshire. Police later said they had been arrested and detained in police custody under the Explosives Substances Act (1883).
It came as a man appeared in court charged with assault after an attack on Lennon at Tynecastle stadium at the Celtic v Hearts game on Wednesday night.
Police were also called to Celtic stadium in Glasgow after a suspect package believed to have contained a bullet and addressed to Lennon was found.
Police launched a major investigation after two bombs were sent to Lennon and one each to lawyer Paul McBride QC and former MSP Trish Godman. A fifth suspect package, addressed to the offices of Cairde Na H'Eireann (Friends of Ireland) in Glasgow, was also intercepted by officers last month.
The two men arrested are expected to appear at Kilmarnock Sheriff Court on Friday.
Football chiefs said the recent incidents had brought shame on Scottish football. Officers arrested a man on Wednesday night after he clambered from the Hearts section of the main stand on to the pitch during a match at Tynecastle stadium in Edinburgh and made towards Lennon.
The manager, who has had to live with round-the-clock security after death threats in the past, was said to have been left "shaken" by the incident.
John Wilson, 26, from Edinburgh, has been charged with breach of the peace aggravated by religious prejudice and assault aggravated by religious prejudice.
He appeared at a private hearing at Edinburgh Sheriff Court. No plea or declaration was made during the hearing and he was remanded in custody.