A fresh takeover bid has been made for Shotover Jet shares but it still falls below what an independent valuation considered was a fair price.

Ngai Tahu Holdings Corporation, which already holds an 82 per cent stake in the adventure company, has upped its takeover offer to 70c per share, an increase of 10c on the original offer.

Both offers were made on the basis that a fully imputed dividend of 1.25cps, already announced, would be received by all shareholders.

Shotover's independent directors reminded shareholders today that a Grant Samuel valuation found that the company's underlying value was in the range of 82c to 94c per ordinary share.

The directors advised shareholders not to accept the offer before considering the Grant Samuel report and a Shotover Jet response to Ngai Tahu's offer, which would be mailed out on Friday.

"Shareholders should carefully evaluate the independent report before making any decision on the offer," they said.

Shotover Jet shares rose to a new high 5c to 70c by 12.30pm today.

The company operates jet boat businesses in New Zealand, a jet boat business in Fiji, and the Rainbow Springs and Farm business in Rotorua.

It posted a full year profit of $4.05 million, down 10 per cent on last year.