Sinn Féin and the cross-community Alliance Party have been targeted as packages containing bullets were posted to the North's legislative assembly at Stormont, it was revealed today.
A string of attacks against public representatives has followed the decision to reduce the number of days on which the Union flag is flown from Belfast's City Hall.
The change sparked sporadic loyalist violence and road blocks, which have continued for most of this month and blighted Belfast city centre trading in the run-up to Christmas.
A spokeswoman for the Police Service of Northern Ireland (PSNI) said: "Police are currently dealing with a number of suspicious packages which have been located in the postroom at Stormont."
Sinn Féin said letters containing bullets and addressed to assembly members Gerry Kelly and Alex Maskey had been sent to Stormont.
The Alliance Party said bullets were posted to party leader David Ford, East Belfast MP Naomi Long and local councillor Gerardine Mulvenna.
An Assembly spokesperson said: "A package was delivered to Parliament Buildings on Wednesday and intercepted by security staff. In line with standard procedures, the package has been passed to the PSNI."
Alliance Party offices have been burned by arsonists in Carrickfergus, Co Antrim, and Ms Long and Mr Kelly have been the subject of death threats before during the recent period of unrest.
Unionist political leaders have unveiled proposals they hope will persuade loyalists to end their ongoing protests in the North over flying the Union flag.
Stormont First Minister and Democratic Unionist leader Peter Robinson and Ulster Unionist leader Mike Nesbitt are to set up a Stormont forum to focus on the flag issue and other areas of concern within loyalism.
Representatives from within that community will be invited to attend and put their views across. The first meeting could be held before Christmas, but a more likely timetable would see proceedings convened early in the new year.
The anticipated development was announced yesterday after another night of violent scenes across the North on Monday linked to the flag dispute.
More than 40 police officers have been injured in almost three weeks of disturbances - first triggered when Belfast City Council voted to reduce the number of days the Union flag flies at City Hall.