Three shops were fire bombed last night in Portadown, Co Armagh, hours after an incendiary device was earlier defused at another business premises.
The RUC had issued appeals for traders to check their premises for suspect packages after the earlier discovery.
A furniture store in Meadow Lane went on fire at around 10.20 p.m., prompting fresh RUC appeals to shopkeepers. The shop was extensively damaged before firemen got the blaze under control.
At around 11 p.m., two more stores were set on fire in the High Street Mall area of the town. A fire at the Jeansters store was quickly extinguished by fire crews, while the damage caused to the Poundstretcher shop was contained at the rear of the premises.
The security forces were continuing their investigations last night but believed incendiary bombs were responsible for the fires.
An incendiary device had been found concealed in clothing in the Next outlet in Meadow Lane at around 11 a.m. yesterday. The area was evacuated and the device was made safe by British army bomb disposal officers.
There had been no warning or claim of responsibility but the RUC immediately put businesses on the alert and called for searches.
Meanwhile, hundreds of loyalists rallied in Portadown in support of the Orange Order members who still insist on their right to march down the nationalist Garvaghy Road. Police prevented several hundred who gathered at one end of the Garvaghy Road from getting through.
At Newtownabbey, Co Antrim, hundreds gathered for a separate protest.