Police investigating the murder of workman David Caldwell at a Territorial Army camp in Derry made two more arrests in the area today, bring to five the number being questioned.
The arrests come as police continue to question two men and a woman detained yesterday after a booby-trapped lunchbox exploded, killing Mr Caldwell in a temporary building at Caw Camp.
Northern Ireland Secretary Dr John Reid described the murder of the civilian worker as a "brutal and cowardly act".
Dr Reid said violence in Northern Ireland is escalating because extreme elements of republicanism and loyalism wish to destroy the peace process.
He said: "There is a myth going around that this violence is only the result of the peace process, as if it never happened before.
"The reality is that there is a lot less violence than there was 10 years ago but it is escalating at present because those extremes on both sides desperately want to kill the peace process and put themselves back centre-stage in dominating the politics by the gun."
