More than a tonne of cocaine has been seized off the east coast of Australia and five men arrested after police raided a suspicious motorboat.

Detectives said they were tipped off about the purchase of a 13-metre-long boat with a large sum of cash in Sydney’s Sutherland shire on 28 April.

Police said they began investigating and intercepted the vessel on Friday as it was travelling towards South West Rocks on the New South Wales mid-north coast.

Officers allegedly found 1,110 blocks of cocaine together weighing more than a tonne on board.

Police estimated this amount of cocaine was worth $623m on the street.

Two men, aged 24 and 26, were arrested on board while another three men, aged 28, 29 and 35, were taken into custody on shore after officers stopped two cars allegedly trying to leave the area.

Searches of Newcastle homes led to police seizing electronic devices, documents, clothing and cash.

The two men on board the boat have been charged with supplying a large commercial quantity of a prohibited drug and participating in a criminal group.

The three men on shore were charged with taking part in supplying a large commercial quantity of a prohibited drug and participating in a criminal group.

All five faced Parramatta bail court on Saturday where they were formally refused bail to appear at Coffs Harbour local court on 15 July.

“Australia’s vast coastline is attractive to organised crime groups, who attempt to exploit this by trying to import drugs using boats,” Australian federal police assistant commissioner Stephen Dametto said in a statement.

“The bad news for them is the AFP will continue to work together with our partners to target organised crime syndicates who wrongly believe they can operate with impunity.”