Ecuador central bank lowers 2012 growth target to 4.8 pct

* Previous growth forecast was 5.4 pct

* Public spending fueled the growth in recent years

QUITO, July 17 (Reuters) - Ecuador's central bank has lowered its 2012 economic growth forecast to 4.8 percent from 5.4 percent previously, according to a report published on the monetary authority's website on Tuesday.

The central bank report did not explain why it decided to lower its 2012 growth target, but the government has warned that Ecuador's economy could suffer if oil prices drop.

In recent years, higher oil revenues together with increased tax collection have allowed the government to ramp up public spending, which has spurred economic growth.

However, the OPEC-member's economy grew 0.7 percent in the first quarter versus the last three months of 2011, the lowest quarter-on-quarter growth rate since the first quarter of 2010.

Central bank data shows that key crude oil exports decreased 0.6 percent in value in the first quarter versus the last three months of 2011.

Growth in the construction sector slowed to 0.3 percent in the first quarter, the slowest quarter-on-quarter growth rate since the last three months of 2009, ac cording to the data.

Ecuador's economy expanded 7.8 percent in 2011, more than double the 2010 growth rate of 3.6 percent and higher than the paltry 0.4 percent in 2009.

The government has vowed to continue spending heavily to spur growth in 2012 as it heads toward a presidential election scheduled for February 2013.

Leftist President Rafael Correa is expected to run for re-election but has yet to make an official announcement.

The country's good economic performance led Standard & Poor's to upgrade Ecuador's long-term sovereign rating to B from B-minus in early June.

But the Correa government has failed to diversify the economy away from its dependence on oil exports and Ecuador could suffer if crude prices continue falling.

"A failure to accumulate savings during a run-up in oil prices means that the dollarized economy now looks highly vulnerable to a sustained period of weaker energy prices," Capital Economics said in a note earlier this month.

Ecuador produces around 500,000 barrels of crude oil a day and is OPEC's smallest member. (Reporting by Eduardo Garcia; editing by M.D. Golan)