MELBOURNE, Aug 23 (Reuters) - Australia's top fuel supplier Ampol Ltd made a NZ$1.97 billion ($1.34 billion) takeover bid for New Zealand peer Z Energy, valuing it at a 24% premium to its last closing price, the companies said on Monday.

Z Energy said it will open its books to Ampol following the NZ$3.78 a share buyout offer, which it said followed three previous approaches that were not publicly disclosed.

Shares of Z Energy soared over 17% on the news to NZ$3.58, their highest since March 2020.

Ampol said acquiring Z Energy would be a "logical growth opportunity" which would give it regional scale.

"I think it's a fantastic deal," MST Marquee analyst Mark Samter said on an Ampol briefing call.

Ampol Managing Director Matt Halliday told analysts the company would be able to use its trading arm to help supply the New Zealand market, where the lone refinery is set to be converted into a fuel import terminal.

Z Energy said Ampol made at least three prior bids ranging from NZ$3.35 to NZ$3.60, verbally and through letters. Ampol said separately it made a first approach on June 2 and acknowledged a second at NZ$3.50 on July 1.

Ampol's shares fell more than 6% as it expects to issue A$600 million ($430 million) in new shares to help fund a deal.

Ampol will have four weeks of exclusive access to Z Energy's books to conduct due diligence, the two companies said.

Ampol said it may have to sell its Gull fuel station business in New Zealand to ease competition concerns, which would help it pay for the acquisition.

The two companies are discussing an option for a partial share consolidation for Ampol and potentially a secondary listing in New Zealand, Z Energy said.

Z Energy was formed when Infratil Ltd and a local pension fund bought Royal Dutch Shell's downstream business in the country in 2010. In 2016, the company expanded further by buying Chevron's local assets. ($1 = 1.4650 New Zealand dollars) ($1 = 1.3976 Australian dollars) (Reporting by Sonali Paul; Additional reporting by Nikhil Kurian Nainan in Bengaluru; Editing by Daniel Wallis and Richard Pullin)