* Geopolitical tensions undermine U.S. dollar
* Oil resumes climb as geopolitical worries grow
* Trichet comments underpin euro (Updates prices, adds quotes, changes dateline; previous LONDON, byline)
By Gertrude Chavez-Dreyfuss
NEW YORK, July 9 (Reuters) - The U.S. dollar weakened on Wednesday, as oil prices rebounded and geopolitical tensions resurfaced with news Iran test-fired missiles and unknown gunmen attacked the U.S. consulate in Turkey.
Iran's state media reported that the country had test-fired nine long- and medium-range missiles, including one which it had previously said could reach Israel and U.S. bases in the region.
"Geopolitical tensions are slightly weighing on the dollar, although, we haven't seen such big moves and we're still within trading ranges," said David Powell, a currency strategist at Bank of America in New York.
Tensions in the Middle East were further exacerbated after three policemen and three gunmen were killed in an attack on the United States consulate in Istanbul.
The dollar index, which tracks the greenback against a basket of six major currencies, fell 0.2 percent on the day to 72.771 <.DXY> in early New York trading.
Rising geopolitical concerns also gave safe-haven currencies like the Swiss franc <CHF=> a bid tone. The dollar fell 0.1 percent to 1.0324 Swiss francs and versus the Japanese unit, it was slightly down at 107.37 yen <JPY=>.
Analysts, however, said geopolitics could soon take a back seat once the macroeconomic news-flow picks up after a lack of first-tier economic releases from U.S. or euro zone on Wednesday.
OIL REBOUNDS
Oil resumed its climb in the wake of Iran's missile test with U.S. crude <CLc1> gaining nearly $2 to above $137 a barrel, further adding to the dollar's bearish tone. Higher oil prices tend to hurt the dollar because the United States is a heavy energy consumer.
Oil had fallen more than $5 on Tuesday after forecasters said an Atlantic hurricane would steer clear of offshore oil platforms but it remained not far off its all-time high of $145.85.
Another mild dollar negative was the fact that Group of Eight leaders did not speak out against the U.S. currency's weakness in the communique ending their three-day meeting.
The euro gained 0.3 percent to $1.5714 <EUR=> and edged up 0.2 percent to 168.71 yen <EURJPY=R>.
Comments on Wednesday from European Central Bank President Jean-Claude Trichet justifying the bank's rate increase last week and reiterating its inflation focus also underpinned the euro, analysts said. See [
]."There is no mistaking the hawkish tone of his comments," said HSBC Bank USA in a research note.
"While there is the very realistic chance that tighter ECB policy will weigh on growth in a manner that is unhelpful to the euro, that sequence of events could well take some time to play out, and interest rate dynamics could play the more dominant and euro-supportive role for much of this summer."
Despite broad U.S. dollar weakness, the Aussie dollar <AUD=> lost ground after a drop in consumer confidence and following a report showing demand for home mortgages suffered the biggest monthly fall in eight years, the latest signs the economy is losing steam. For more see [
].The Aussie fell to a near three-week low of US$0.9477. It last traded at US$0.9531. (Editing by Theodore d'Afflisio)