* To cut its purchases of nominal bonds to 5 pct

* Change effective immediately

* To buy minimum C$150 mln at July 15 sale of 5-yr bonds (Adds details)

TORONTO, July 9 (Reuters) - The Bank of Canada is cutting the minimum amount of nominal bonds it purchases for balance sheet purposes at its auctions to 5 percent.

The change, effective immediately, has no implications for monetary policy, the central bank said on Thursday.

"This will assist in bringing its holdings of Government of Canada securities more in line with the composition of the government's stock of marketable debt, consistent with the Bank of Canada's policy for the management of its balance sheet," the central bank said.

The Bank of Canada said it will continue to indicate its plans for minimum purchases for each offering of nominal bonds. Holdings of maturing bonds, if any, will also be published.

It said it would buy a minimum of C$150 million of the five-year bonds, due Dec. 1, 2014, at its July 15 auction. [ID:nTOR004752]

The central bank made a similar move in November. At the time, the Bank of Canada said it would decrease its participation at nominal bond auctions to 10 percent for securities in which the central bank holds less than 10 percent of the amount outstanding. It would otherwise cut its participation to zero. (Reporting by Ka Yan Ng; editing by Peter Galloway)