* UK volume falls 20 percent in April from October
* North American volume down to $527 billion in April
* U.S. dollar remains most heavily traded currency (Adds North American FX volume, quote, details; changes byline, dateline, previous LONDON)
By Naomi Tajitsu and Gertrude Chavez-Dreyfuss
LONDON/NEW YORK, July 27 (Reuters) - Average daily turnover in the UK foreign exchange market totaled $1.356 trillion in April, down 20 percent from six months ago, as spot volumes slumped during the global financial crisis, a survey by the Foreign Exchange Joint Standing Committee showed on Monday.
In North America, the average daily volume in total over-the-counter currency instruments fell 26.3 percent year-on-year in April 2009 to $527 billion, according to a separate survey by the Foreign Exchange Committee (FXC). That was the lowest average volume since October 2005.
"The decline in volumes evidenced by the latest survey appears to be consistent with declines in global leverage and asset valuations during the reporting period," said Richard Mahoney, chair of the Foreign Exchange Committee, a group of major domestic and foreign banks.
In its semi-annual survey, the Foreign Exchange Joint Standing Committee said overall turnover fell due to a 28 percent fall in spot transactions particularly with banks and other financial institutions.
Despite the fall, the figures showed turnover in the UK market continues to dwarf that in New York, Singapore and other reporting financial centers, keeping intact London's position as the global hub of currency trading.
The total volume of "traditional" FX products traded -- which include spot, outright forwards, non-deliverable forwards and FX swaps -- was $1.269 trillion, down from $1.573 trillion in the last survey taken in October 2008, the UK survey said.
Average daily reported turnover of over-the-counter FX instruments, including FX options and currency swaps, was $87 billion in April, down 31 percent from six months ago, when it was $126 billion.
Figures have shown that average FX payment instructions peaked in October, around the time of a massive exodus out of higher-risk investments into safe-haven assets following the collapse of Lehman Brothers.
U.S. DOLLAR MOST HEAVILY TRADED
The dollar remained the most heavily traded of all currencies, with its share of total transactions rising to 84.3 percent in April, up from 82.6 percent in October.
The U.S. currency's share was nearly double that of euro transactions, which accounted for 45.0 percent in April, inching down from 48.6 percent six months ago.
Sterling's share of total transactions was 18.7 percent, flat from October, while that of the yen slipped to 16.9 percent from 19.6 percent.
Because two currencies are featured in every transaction, the sum of percentage shares in overall turnover add up to 200 percent, rather than 100 percent.
Euro/dollar was the most heavily traded currency pair in the UK, accounting for $434.1 billion, or 32.0 percent, of all transactions. Still, its share was down from $568.5 billion, or 33.5 percent, in October.
Sterling/dollar transaction were the next most commonly traded pair, totaling $180.8 billion, down from $221.8 billion. Its percentage share was 13.3 percent, little changed from 13.1 percent.
Rounding out the top three trading pairs was dollar/yen, which accounted for 12.5 percent of all transactions, down from 13.5 percent.
Meanwhile, declines in the average daily volume in North America were broad based and were reported across all currency pairs, instrument types, counterparty types, and execution methods.
Spot FX transactions saw a daily average volume of $294 billion in April, down from $393 billion a year earlier, the survey showed. Meanwhile, daily FX options turnover was nearly cut in half to $18 billion from $34 billion in April 2008.
But spot market transactions conducted by the top one-fifth of dealers based on market share remained elevated following the rise seen in the October 2008 survey results, continuing to suggest increased market concentration over the past year, the survey said.
Similar surveys for April were carried out in Singapore, Canada and Australia. (Editing by Andrea Ricci)