Don Brash says everyone should be concerned about political interference regarding matters at America's central bank. 

US Federal Reserve Chair Jerome Powell says he's now embroiled in a criminal investigation because he didn't cut interest rates as much as Donald Trump wanted. 

Trump denies involvement but is standing by calls for Powell to be replaced. 

RBNZ Governor Anna Breman signed a joint statement in support of Powell, saying he's highly respected, with an unwavering commitment to the public interest. 

But Winston Peters rebuked her for it, saying she needs to stay in her New Zealand lane and stick to domestic monetary policy. 

But Brash, a former New Zealand Reserve Bank Governor, strongly backs Breman, saying that Peters is in the wrong in this situation.  

He told Andrew Dickens it's in everyone's interests for the Federal Reserve to be able to make its own independent decisions, free from interference. 

Brash says the US dollar is the backbone of the world economy and the world monetary policy system, and anything that jeopardises that affects everyone. 

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