The bumper number underlines a dramatic change on Comex since March, when the coronavirus crisis weakened links between New York, the world's main gold futures trading venue, and London, the biggest centre for storing and trading physical bullion.

The assumption that gold could be quickly shipped from London to New York to settle contracts broke down when lockdowns grounded passenger planes used to transport it and closed refineries that shape metal to fit CME specifications.

Since then, futures prices have typically been higher than gold prices elsewhere in the world, incentivising traders to ship metal to New York to profit on the difference.

Stockpiles in Comex-registered vaults of gold deliverable against the exchange's main contract have leaped to 1,016 tonnes from 276 tonnes in late March, CME data shows.

Deliveries against active contracts have soared - from just 8,234 contracts representing 26 tonnes of gold in February to 31,666 contracts (98 tonnes) in April and 55,102 contracts (171 tonnes) in June.

On Thursday, traders said they intended to deliver against 32,732 contracts expiring in August, according to the CME.

Some 47,236 contracts were still active on Friday that will either be delivered against by the end of August or swapped for contracts expiring in later months.

By Peter Hobson