WASHINGTON (AP) — A key regulator is urging Congress to go beyond an Obama administration proposal and impose comprehensive oversight on the sprawling, complex market for financial derivatives blamed for worsening the credit crisis last fall.

In testimony before the House Agriculture Committee, Commodity Futures Trading Commission Chairman Gary Gensler says "the law must cover the entire marketplace, without exception."

The administration is seeking to increase the transparency of the $600 trillion global derivatives market and has proposed that big investment banks that trade derivatives be subject to requirements for holding capital reserves against risk.

The House Agriculture and Finance committees have agreed to a similar measure, but Gensler wants the lawmakers to tighten the legislation.