Central banks have emerged as some of the biggest buyers of gold this year, with purchases hitting their highest level in six years, according to analysts at Macquarie.

Central banks have bought a total of 264 tonnes of gold this year, "by far the most at this stage of the year of any period in the last six years," the bank said.

While gold buying has been dominated by Russia, Turkey, and Kazakhstan, Poland also bought gold for the first time since 1998, Macquarie said.