Norman and Shearer victims of pranksters

Pranksters have signed up Green Party co-leader Russel Norman and Labour leader David Shearer to the Mighty River Power share sale pre-registration.

They're both committed opponents of asset sales and say the fact they were signed up shows the pre-registration process is "dodgy".

More than 280,000 New Zealanders have pre-registered for shares - an expression of interest, which isn't a commitment to buy any shares.

Dr Norman says he received an automatic acknowledgement from the pre-registration website on Saturday confirming he had pre-registered.

"We contacted Treasury and they said it had been done in jest - I don't know how the Treasury knew that, it seems to me it could have been done in malice as much as in jest."

Dr Norman says the fact he was signed up shows the process is "pretty dodgy" and doesn't have robust security checks.

"When the email popped up it seems to me the National Party might be up to its dirty tricks, I don't know whether it is or not."

Dr Shearer also received an acknowledgement from the website saying he had pre-registered.

"It just shows how shonky this process actually is," he said.

State Owned Enterprises Minister Tony Ryall says the fact that both men discovered they had been signed up and cancelled the pre-registration shows the system's security is sound.