Stock on Waiheke Island will continue to be tested every 48 hours until the end of the potential incubation period for foot-and-mouth disease, on May 23.
However, police are growing increasingly confident that the threat is a hoax.
Anyone thinking of heading for the island this weekend for a look
at efforts to contain the supposed disease outbreak should stay at home, say MAF officials.
The Ministry of Agriculture and Forestry issued the advice yesterday as police claimed overseas support for their assessment that the threat is a hoax.
"MAF advises that those planning on making a special trip to Waiheke to look at the response [to the threat] are wasting their time - there is nothing to see," the ministry said.
"However, those with a legitimate reason to travel to the island should feel free to do so." Police say Victorian state counterparts support their assessment that the extortionist's letter contained empty threats.
"The letter has been thoroughly examined and an evaluation made of its contents," said Assistant Commissioner Peter Marshall.
"The assessment is that the letter presents a very low level of threat."
Yesterday was the day the extortionist also threatened to spread the disease to the mainland if the Government did not give in to demands for money and a change to tax policy.
It was also the first day the agency could have expected to notice visible symptoms of the disease.
Spokesman Brett Sangster said all but one of the 52 livestock owners had been found, and no non-feral animals had escaped the first checks.
A police spokesman said that although investigators had received general information from the public in their hunt for the extortionist, they had no specific leads.
The person responsible faces up to seven years in jail.
Federated Farmers has launched a national appeal for hay for Waiheke farmers unable to sell stock off the island during the scare.
