WASHINGTON (Reuters) - A member of the top U.S. derivatives regulator criticized his own agency on Thursday, charging that the Commodity Futures Trading Commission has failed to coordinate oversight of swaps effectively with its international counterparts.

After the 2007-2009 financial crisis, regulators worldwide clamped down on risk-taking in the $710 trillion global swaps market, which is dominated by large U.S. banks and had long received little oversight.

Coordinating their rulemaking has been tough, and CFTC member J. Christopher Giancarlo said the commission had failed in that effort.

In 2013 three trade associations sued the CFTC, challenging its authority to regulate cross-border swaps. While the court largely backed the CFTC, it required the commission to address costs and benefits of some of its cross-border rules.

On Thursday, the CFTC released 83 pages responding to the court's request, saying compliance costs may vary across countries, while adding that there is no need to substantively change the rules.

It also released a statement from Giancarlo in which he said he dissented from the response, saying "it must be noted that the commission has repeatedly failed to coordinate effectively with foreign regulators to implement global standards in financial markets.

"The lack of harmonization in the implementation date for margin for uncleared swaps is the latest example. The result for financial markets has been a complex, conflicting and costly array of CFTC cross-border regulations," he said.

The European Commission recently announced that it is delaying implementation of collateral requirements for uncleared swaps, which do not go through a middleman.

Giancarlo said the CFTC's approach has "allowed foreign regulators to respond in kind."

CFTC Chairman Timothy Massad said the commission has made progress over the past several years in harmonizing regulation and has accomplished much in central clearing, oversight of swap dealers, trading and reporting.

In a statement, he pointed to the same uncleared swaps rule as an example, saying the CFTC had aligned the substance of its requirements with Europe's and the European Commission has "made clear that this delay will be modest."

"Regulations are implemented by individual nations, or unions of nations, each of which has its own legal traditions, regulatory philosophies, political processes, and often, statutory timetables," Massad said. "There will always be differences, just as there are in every other area of financial regulation. The more important story is we are making good, steady progress."

(Reporting by Lisa Lambert; Editing by Dan Grebler)