* Mining stocks hit their lowest in more than 2 months

* "Big Four" banks extend losses

* RBNZ likely to keep interest rates at record lows - Reuters poll

Sept 22 (Reuters) - Australia shares closed weaker for a fourth straight session on Tuesday as concerns about fresh pandemic lockdowns across Europe sapped global risk appetite and sent commodity prices lower.

Mining stocks led losses on the benchmark ASX 200 index, which fell 0.7% to end the session at its lowest since June 15.

Another COVID-19 wave in Europe has unsettled investors and British Prime Minister Boris Johnson is considering a second national lockdown, sparking worries about a deeper economic slowdown.

Oil prices plunged overnight and iron ore fell for a second session as rising cases also stoked worries about global demand.

Equity markets had been pricing in a decent recovery, thinking that most countries were coming off lockdowns for good, said Damian Rooney, director of equity sales at Argonaut.

"I think that there are going to be some speed bumps ahead," Rooney added.

Australia-listed shares of BHP Group fell the most in nearly two weeks, while Rio Tinto and Fortescue Metals slumped 2.4% and 2%, respectively.

Global banking stocks continued to reel from reports citing that several lenders transferred more than $2 trillion in illicit funds despite red flags about the origins of the money.

Australian lenders extended the decline, with National Australia Bank dropping the most by 2.4%.

New Zealand's NZX 50 index snapped a three-day losing streak to end 0.6% higher.

The central bank is likely to keep interest rates at a record lows at its meeting on Wednesday, having lifted restrictions across almost the entire country and signals that the economic fallout may be milder than expected.

Medical device maker Fisher & Paykel Healthcare Corp and casino operator Skycity Entertainment were the top percentage gains on the benchmark, jumping more than 3% each. (Reporting by Deepali Saxena in Bengaluru, Editing by Sherry Jacob-Phillips)