A massive arsenal of weapons destined for criminal gangs in Northern Ireland and the Irish Republic has been recovered in a major cross-border police operation that also extended to the Netherlands, police in Belfast said Friday.

Hugh Orde, the police chief of Northern Ireland, said a total of 230 handguns, 10,000 rounds of ammunition, 450,000 euro in cash and drugs with an estimated street value of over four million euro were seized in the operation.

Six people were in custody in Dublin, Belfast and Amsterdam after forces from the three jurisdictions swooped on the suspected trafficking ring this week.

Among them were three Dutch men and a Brazilian woman, who were detained by police in Amsterdam following a tip-off from detectives in Northern Ireland.

Dutch police seized 165 firearms in a car and at a factory in the Amsterdam wrapped and ready for delivery. It is understood the weapons were bound for Ireland.

"We have a large number of lethal weapons that were being distributed across Europe and, in particular, our concern was Northern Ireland and our colleagues in the (Irish) Republic," said Orde.

"This is a massive blow (against the gang)," he added.

Officers warned that guns and bullets had in the past found their way into the hands of dissident republican forces in the province.