Conor English, brother of Finance Minister Bill, has been appointed to advise the Reserve Bank on monetary policy.

Conor English, the brother of Finance Minister Bill English, has been appointed by the Reserve Bank to advise it ahead of interest rate decisions.

On Thursday the central bank said English, the former chief executive of Federated Farmers, had been appointed as a "part-time external monetary policy adviser".

Tony Caughey, an Auckland company director has also been appointed to the role.

"The appointees take part in the provision of advice to the Bank's Governing Committee leading up to the setting of the Official Cash Rate eight times a year. The appointees' roles will start with the June Monetary Policy Statement."

One of the key aspects of New Zealand's monetary policy is that it is entirely independent of the Government. Last week the bank's deputy governor gave a speech which many commentators took as critical of the Government for the absence of a tax on property speculation.

READ MORE: RB call to look at untaxed property gains

The RBNZ statement made no reference to Conor English's relationship to the Finance Minister.

A spokeswoman for Bill English said the Finance Minister was not consulted on his brother's appointment or given advance warning of Thursday's announcement.

The Reserve Bank declined to comment beyond its statement.

"The Reserve Bank employs these advisers to bring valuable additional outside perspectives into our processes and to help ensure the Bank is well-informed about developments in the New Zealand economy," RBNZ Governor Graeme Wheeler said.

"These appointments add significant value to the Bank by bringing in fresh viewpoints."