New Zealand shares ended flat with a positive bias on Tuesday's close as investors look forward to easing tensions between the US and China after their trade discussions in London were extended to a second day.

The S&P/NZX 50 Index was little changed to close at 12,564.42.

The two superpowers will discuss negotiating a deal over rare earth minerals and solve their tariff dispute, Reuters reported.

"Our expectation is that after the handshake, then immediately after the handshake, any export controls from the U.S. will be eased, and the rare earths will be released in volume, and then we can go back to negotiating smaller matters," said White House economic adviser Kevin Hassett, as quoted by Reuters.

New Zealand's Finance Minister Nicola Willis said on Tuesday that she wants the Reserve Bank of New Zealand's monetary policy committee to meet more frequently, flagging lengthy gaps between meetings in summer, according to a separate Reuters report.

"I'm particularly concerned about the 12-week break over summer, which is a long time to go between meetings. The central banks of England, Canada, Australia, and the United States have shorter breaks and meet more frequently," she said, as quoted by Reuters.

In domestic news, New Zealand's Light and Heavy Traffic Indexes both fell in May, down 0.5% and 3.0% month-on-month, respectively, according to a Tuesday report by ANZ.

Further, ANZ Bank said spending in New Zealand using its cards fell 0.1% month-on-month in May, with softness in apparel and hospitality spending and recovering durables spending.

Also, New Zealand's natural gas reserves as of Jan. 1 declined by 27%, compared with last year, according to data released by the Ministry of Business, Innovation and Employment.

In corporate news, Warehouse Group (NZE:WHS) will be removed from the S&P/NZX 50 index and will be replaced by Briscoe Group (ASX:BGP, NZE:BGP), following a quarterly review.

Scales (NZE:SCL) expects underlying net profit after tax for the year to be in the range of NZ$40 million to NZ$45 million, up from its previous guidance of between NZ$37 million and NZ$42 million, citing strong performance in horticulture volumes in the first half.