A touchline attack on Celtic manager Neil Lennon has "brought shame on Scottish football", the club's chief executive said today.
Officers arrested a man last 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.
Celtic chief executive Peter Lawwell said last night's events brought "shame on Scottish football".
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 this afternoon. No plea or declaration was made during the hearing and he was remanded in custody.
Meanwhile, in a separate incident, two men were being held by police in connection with an investigation into parcel bombs sent to Lennon and two high-profile supporters of the club.
Two bombs were sent to Lennon and one each to lawyer Paul McBride QC and former MSP Trish Godman.
The men, aged 41 and 43, were detained under the Explosives Substances Act 1883 after officers raided a number of properties in Kilwinning, Ayrshire.
The police operation was launched at around 6am today.
A package sent to Lennon on March 4 was traced to a postbox in Gladstone Road, Saltcoats, Ayrshire, while one addressed to Mr McBride was found at a postbox in Montgomerie Terrace in nearby Kilwinning.
Police were also called to Celtic FC's stadium in Glasgow today after a suspect package was found.
The package is believed to have contained a bullet and was addressed to Lennon.
Police cordons were set up near properties in Innerwood Road, Kilwinning, and Links Road in Saltcoats.
A police spokeswoman confirmed that officers had visited other addresses, but only to speak to people they believed could help them with their inquiries.
Chief Superintendent (CS) Ruaraidh Nicolson, of Strathclyde Police, said they had carried out a "lengthy investigation" over the past month or so.
He said: "We've had about 100 officers working on it up until this point in time and even more this morning in terms of the operation."
Last month, Strathclyde Police said the two packages sent to Lennon, and the two others, were "designed to cause real harm to the person who opened them".
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.
All of the parcel bomb packages were found during March and last month.
After last night's incident, trouble flared in the Celtic section of the stadium, with fans appearing to fight with police and stewards. The Glasgow side won the game 3-0.
Lothian and Borders Police said there were a number of incidents during the match, including some violent disorder which would be fully investigated.
Hearts and the Scottish Premier League (SPL) have also launched investigations.
SPL chief executive Neil Doncaster told BBC Radio Scotland the incident was "wholly unacceptable" and "disgraceful".
Scotland's First Minister Alex Salmond branded such behaviour "utterly unacceptable".
Earlier this week, seven people appeared in court charged with possessing an imitation firearm after they were arrested outside Celtic's training ground.
Mr Lawwell said: "It is intolerable that any football club, or individual, going about their lawful business in the name of sport should be subjected to this ongoing campaign of hatred and intimidation.
"This is Scotland's shame and it is high time Scotland addressed it."
He said that Lennon deserved respect for the strength of character and resilience he has shown during the "campaign of intimidation" he has endured.