Police officers and vehicles are seen behind police cordon, in Christchurch, New Zealand in this still image taken from video April 30, 2019. TVNZ via Reuters TV

WELLINGTON (Reuters) - A man in Christchurch was charged in court on Wednesday with possessing explosives, ammunition and offensive weapons a day after police found a suspected explosive device in the city where 50 Muslims were killed in attacks on two mosques in March.

Police said the 33-year-old suspect had no known link to those attacks. He was charged with three counts of possession of explosives and possession of ammunition and two counts of possession of an offensive weapon, according to an emailed statement from New Zealand Police.

Police had arrested the man at a service station in eastern Christchurch on Tuesday and bomb disposal officers dealt with the suspected explosive device found at a vacant property in another suburb of the city.

“We are not seeking anyone else in relation to the incident. There are no known links between the 33-year-old man and the Christchurch attacks on March 15,” the statement said, adding that police would refrain from further comment while the case was before the courts.

New Zealand’s security has been on high alert, though the national security threat was downgraded to ‘medium’ last month following the massacre at two mosques in the South Island city.

Fifty people were killed and dozens wounded in attacks on the Al Noor and Linwood mosques during Friday prayers on March 15, the worst peace-time shooting in New Zealand history. Tuesday’s incident was about a kilometer from the Linwood mosque.

Authorities have charged Australian Brenton Tarrant, 28, a suspected white supremacist, with 50 counts of murder.