As pro-British marchers assembled for a day of province-wide demonstrations, police said they had arrested two men after the murder of three Catholic children in a fire bomb attack on their home yesterday. The killings were condemned by the Orange Order, an exclusively Protestant brotherhood that holds mid-July marches each year to commemorate 300-year-old British victories over the native Irish.

"Two men have been arrested this morning in connection with the suspected sectarian arson attack at Ballymoney early yesterday," a police spokesman said.

The killings sent shock waves through both communities in the bitterly divided British-ruled province and cast a shadow over hopes of stability in the wake of a peace deal hammered out by rival politicians in April. A march by several hundred members of the Orange Order along Belfast's Lower Orrmeau Road, which has sparkedrioting and unrest in the past, was initially delayed by a hoax bomb alert.