Belfast Lord Mayor Mr Alex Maskey today said he received a death threat from the loyalist Orange Volunteer Force a day before he organised an anti-sectarian rally in the city.
Sinn Féin's first mayor of the city said he was concerned, but would not be intimidated, after a bullet was received in the post on Friday morning, hours before thousands attended the rally outside City Hall.
He said: "It just ironic on the day that you're trying to establish a campaign on anti-sectarianism that yet again you become, let's say, a victim almost of more sectarianism.
"So I think it's just important to highlight that this sectarian problem is still rampant with us but as far as I'm concerned it certainly will not detract me from doing what I know that I have to do as a civic leader."
The threat to Mr Maskey emerged as trade union officials held emergency talks after staff at three Belfast hospitals began work this morning with death threats hanging over them from both republican and loyalist terrorists.
The Catholic Reaction Force said it would kill three unnamed members of staff of the Royal Victoria Hospital in west Belfast and the Mater in the north of the city who had links to the security forces if they turned up for work today.
The threats, which were issued yesterday to one of the hospitals and to a Belfast newsroom, have been condemned by management and unions.
Ms Patricia McKeown, of the health service union Unison, said the Ulster Freedom Fighters had then issued a threat against Catholic staff in the Mater and Ulster hospitals.
In a statement, management and staff called for the threats to be lifted.
A police spokeswoman confirmed that they were investigating the matter.
Earlier, postal workers in Derry defied death threats to return to work.
Despite fears that someone inside the city's Royal Mail operation was targeting colleagues, a ballot narrowly backed resuming halted deliveries.
After a loyalist organisation issued a statement denying that there was any threat to Catholics, Mr Charlie Kelly, of the Communications Workers Union, said staff were still far from reassured.
"There's a lot of people in our office are genuinely concerned there's someone in the office in Derry is fingering staff for whatever reason," he said.
Workers at the sorting office in Great James Street withdrew services over the weekend in protest at the death threat.
But the decision to return to work came after the North Antrim and Derry Independent Ulster Loyalists denied "spurious" claims that a member of staff had been targeted.
Tensions in the city have spiralled since construction worker Mr David Caldwell was killed in a dissident republican bomb attack last week.
Loyalists had vowed to take revenge for the murder of the ex-Ulster Defence Regiment soldier.
However workers from across the city marched in protest at the sectarian killing today. The march - organised by the Derry Trade Union Council - started at the scene of Thursday's bomb attack and proceeded to Guildhall Square. PA