* Euro falls vs dollar after ECB leaves rates unchanged
* Trichet: important U.S. expresses support for dollar (Recasts, updates prices, adds comment, changes byline, dateline, previous LONDON)
By Nick Olivari
NEW YORK, June 4 (Reuters) - The euro fell against the dollar on Thursday in volatile trading following the European Central Bank's decision to kept interest rates unchanged.
A comment by ECB president Jean-Claude Trichet at a news conference that it was important that Washington had expressed support for a strong dollar also boosted the dollar against the euro zone single currency.
The ECB kept rates on hold at a record low 1.0 percent but said it expected a much sharper recession in the euro zone this year than previous forecasts.
The bank also said it would buy 60 billion euros in covered bonds, spread across the euro zone, in both primary and secondary markets. The bonds would be rated AA or equivalent.
"Trichet would not comment on any possibility for future purchase programs, either expanded covered bond or asset purchases, and he said there was no decision one way or the other," said Michael Woolfolk, senior currency strategist at Bank of New York-Mellon in New York. "He did not want to address it because he though it would create market expectations."
"He also commented that he did not consider current rates to be necessarily a bottom, which leaves the door open for further cuts in the future," Woolfolk said.
The euro was last down 0.2 percent at $1.4122, according to electronic trading platform EBS, having swung between a peak of $1.4242 and a low $1.4070 over the global session.
Trichet said he appreciates the U.S. government's 'strong dollar' statements.
"I would say it's very important and we appreciate enormously that the U.S. authorities are repeating that a strong dollar is in the interests of the United States of America, which has been repeated by the Secretary of the U.S. Treasury recently," Trichet said.
The dollar index, which measures the dollar against a basket of six currencies, was 0.1 percent higher at 79.575.
Earlier, the Bank of England left key rates unchanged at a record low 0.5 percent and stuck to its 125 billion pound target for quantitative easing as expected.
The pound was last 0.6 percent lower against the dollar at $1.6190, according to Reuters data.
The Canadian dollar dipped against the U.S. currency on Thursday after the Bank of Canada kept rates unchanged, as expected, but acknowledged the economic threat posed by the recent sharp appreciation of the Canadian currency.
The Canadian dollar fell 0.4 percent to C$1.1081, according to Reuters data.
The Canadian central bank made no mention in its statement of unconventional monetary policy easing, such as printing money to buy securities, signaling it maintains the view that further stimulus is not required any time soon. (Additional reporting by Mary Angela Rowe; Editing by James Dalgleish)