Commodities markets regulators on both sides of the Atlantic announced further measures to oversee oil trading as US lawmakers continue to worry that financial speculators can exploit a “London loophole” to sway markets.

The Commodity Futures Trading Commission, the US watchdog, and its UK counterpart, the Financial Services Authority, added new conditions to an agreement to jointly patrol trading in global benchmark oil contracts. They include letting both agencies review trade execution and audit data, sharing disciplinary notices, and visiting exchanges typically outside their jurisdiction.