Rebels issue new threat

LAGOS--Nigerian insurgents released four kidnapped foreign contractors on Monday but immediately vowed to press home a series of violent attacks against the country's key oil and gas industries.The hostages - an American, a Briton, a Bulgarian and a Honduran - were handed over to the Bayelsa State government before dawn, its spokesperson Welson Ekiyor told AFP by telephone from the oil-rich but restive Niger Delta.The oilmens' employers and home governments confirmed that the men had been released after being held for 19 days at secret locations in the delta swamps, and said they would get medical checks before flying home to their families.