Interest rate derivatives market totals $448.7 trln

* Central counterparties hold 44 pct -TriOptima

* Compares with BIS figure of $437.2 trln for June 2009

LONDON, April 29 (Reuters) - The global interest rate derivatives market amounted to $448.7 trillion as of March 31, according to an industry-sponsored report, which was roughly line with existing regulatory data.

Amid intense debate over derivatives in the wake of the financial crisis, the International Swaps and Derivatives Association (ISDA) picked financial services firm TriOptima to collect the data to make over-the-counter markets more transparent and easier to regulate. [ID:nL5525440]

According to the TriOptima report on Thursday, central clearing houses held 44 percent of overall gross notional value, the 14 biggest dealers 22 percent and other dealers 32 percent.

Interest rate swaps totalled $322.2 trillion, while forward rate agreements, options and other types of contracts accounted for the remaining $126.5 trillion.

The latest Bank for International Settlements data for June 2009 showed interest rate contracts as the single biggest market out of the nearly $605 trillion global total in derivatives at $437.2 trillion, with nearly $342 trillion in swaps.

Financial institutions have been reporting data on interest rate derivatives to regulators since Jan. 15, said TriOptima, which was recently acquired by interdealer broker ICAP (IAP.L).

Thursday was the first time that the repository made its data public.

"This is an important step in the industry's continued efforts to provide additional transparency in the OTC derivatives marketplace," said David Halliden, chairman of the repository's governance committee and an executive director at JP Morgan, in a statement.