* ECB holds rates at 1 percent for fourth month running
* Trichet sees very gradual recovery from recession
* ECB staff upgrade economic forecasts
* ECB keeps rate on 12-month finance at 1 percent
(Adds Trichet comments, detail, analyst comment)
By Marc Jones and Sakari Suoninen
FRANKFURT, Sept 3 (Reuters) - The European Central Bank kept interest rates unchanged at a record low of 1.0 percent on Thursday, and warned that now was not the time to withdraw state support as economies emerge slowly from recession.
President Jean-Claude Trichet said the euro zone faced a very gradual recovery but he stressed it was too early to end exceptional ECB measures to boost the economy. ECB staff also raised their estimates for euro zone GDP this year and next, while inflation estimates were edged higher.
Trichet announced the ECB would pump more one-year funds into the financial system at just 1 percent interest later this month.
"There are increasing signs of stabilisation in economic activity in the euro area and elsewhere," he told a news conference. "This is consistent with the expectation that the significant contraction in economic activity has come to an end and is now followed by a period of stabilisation and very gradual recovery."
Germany and France, the region's biggest economies, unexpectedly bounced out of recession in the second quarter. The overall euro zone economy shrank only 0.1 percent against the previous three months, following a 2.5 percent drop in January-March.
However, asked about how long the ECB would keep up its ultra-loose policy, Trichet said: "Today is no time to exit."
In an attempt to dampen expectations of a full-blown recovery, Trichet said it was vital that markets demonstrated "prudence and caution" and warned that the 16-nation bloc faced a decidedly "bumpy road" ahead.
Economists worry that the momentum will be lost once central banks and governments around the world begin to take away the emergency support measures built up during the crisis.
They have also raised doubts about the speed and sustainability of any recovery because unemployment, which reached 9.5 percent in July, is at the highest in more than 10 years.
STAFF PROJECTIONS
Against a backdrop of encouraging data in recent weeks, ECB staff lifted their economic forecasts.
New quarterly staff projections put gross domestic product growth in the 16-nation region at between -0.5 and +0.9 percent next year, giving a midpoint of +0.2 percent, compared with a range of -1.0 percent to +0.4 percent in the June forecasts.
ECB staff also upgraded their projections for this year, and said they expected GDP to fall between 4.4 and 3.8 percent in 2009, a slightly smaller contraction than the 5.1 to 4.1 percent range given in June.
The ECB expected inflation to remain subdued and price stability to be maintained over the medium term, Trichet added.
All 80 economists polled by Reuters had forecast the decision to keep rates at their current all-time low for the fourth month running and markets were little moved by the decision.
Trichet stuck to the line that the euro zone's record-low interest rates remained "appropriate", bolstering expectations that the ECB won't raise them until the third quarter next year at the earliest.
"It's absolutely no shock that both the refinancing rate and the deposit rates have been left on hold. Indeed previous talk about a possible reduction in the refi rate has all but disappeared given the signs of recovery through much of the euro area," said Investec economist Phillip Shaw.
Sweden also kept interest rates on hold earlier on Thursday.
The need for caution on the nascent economic recovery was underscored as ECB policymakers met. Euro zone retail sales fell unexpectedly in July, data revealed, a reminder that demand remains fragile at best.
TENDER INTEREST
Trichet confirmed the ECB would offer banks unlimited 12-month funds at a flat rate of 1.0 percent at an operation later this month, offering no sign of easing up on its unconventional measures to support the economy.
In late June, the ECB flooded markets with a record of 442 billion euros of one-year funds, which they are still digesting, in an effort to kickstart lending.
The ECB had previously said two other such operations, scheduled for September and December, could be at a higher rate. But Trichet said: "This decision (to keep the rate at 1 percent) should promote the extension of credit to the euro area economy and therefore further underpin its economy."
Economists expect the ECB will bump up its lending rate as one of its first steps to unwinding all the emergency support that it has put in place.
Trichet sidestepped repeated questions on whether the ECB had considered increasing the price of one-year funds this time around, or whether it was considering doing so in December.
Economists polled by Reuters expect unchanged ECB benchmark rates until the third quarter of next year and investors have eased back on their bets for early tightening. (For a graph of world interest rates, please double-click on: http://graphics.thomsonreuters.com/RNGS/ECO/RATES.jpg) (Reporting by Marc Jones, additional reporting by Kirsten Donovan in London; editing by David Stamp)