Labour Councillor Frank McBrearty clashed with Fianna Fail councillor Seamus O Domhnaill.
Cllr McBrearty had an emergency motion before the council seeking extra funding for roads on four school routes in the Stranorlar electoral area.
When Cllr O Domhnaill went to object to the motion because the roads funding allocation had already taken place, Cllr McBrearty reacted angrily.
He told the Fianna Fail man: “You never seem to object to anyone else’s motions when they are tabled.”
As Cllr O Domhnaill tried to speak, Cllr McBrearty told him: “I’ll put you in your box.”
Cllr O Domhnaill complained that he had been threatened, but Cllr McBrearty insisted: “That is not a threat. It’s a promise.”
The row flared later when Cllr O Domhnaill went to speak again on the issue.
“I did not threaten anyone,” said Cllr McBrearty. “I want you to define what you mean by threat because I am being accused of a very serious criminal offence and I did not issue a threat.”
The Labour man threatened to leave the chamber as Mayor Noel McBride ordered him to be quiet or face ejection.
On the issue of the poor roads, Cllr McBrearty said he wanted to “ensure the safety of schoolchildren using those roads.”
The roads needed €250k of funding, he said.
Five councillors voted for the motion. Twelve voted against it.