* Creditors take first step in restructuring drive
* South Korean exports to key markets tumble a third
* President Lee faces fresh pressure from deadly fire
By Kim Yeon-hee and Yoo Choonsik
SEOUL, Jan 20 (Reuters) - South Korean banks on Tuesday cut off credit lifelines for two firms, taking the first step in a corporate restructuring drive triggered by the impact of the global downturn which new data shows is hitting exports hard.
Creditor banks also announced they were putting 14 builders and ship makers under rescue plans, which follow pressure from the government trying to prevent a prolonged economic downturn from sparking a wave of corporate failures and job losses.
"There emerged a need for a swift corporate restructuring to remove uncertainty in the financial markets because worsening liquidity problems at companies deepen the economic slump," the Financial Services Commission, the top financial regulator, said in a statement.
The Korea Federation of Banks said it would launch a second credit risk assessment of construction and shipbuilding firms not included in its initial review of 112 companies.
The move comes amid signs that the global downturn is biting hard into the performance of Asia's fourth largest economy.
Data showed that exports to China, South Korea's biggest market, and to the European Union fell by more than a third in December over a year earlier, with shipments to other big markets also falling sharply.
And economists in a Reuters survey estimated South Korea's economy contracted in the last quarter of 2008 by its biggest since the Asian financial crisis a decade ago and predicted the slump would last.
South Korean authorities have repeatedly promised to take decisive and pre-emptive measures to prevent corporate problems adding to the woes of the economy.
On Tuesday, in a nod to his sagging popularity, President Lee Myung-bak replaced some of his top economic officials including his finance minister who has been widely criticised for failing to do enough to protect the economy from the global meltdown.
WORST SINCE 1997/98 CRISIS
The move is aimed at speeding up efforts to revive the economy, widely seen as headed for its first recession in 11 years.
Economists polled by Reuters said gross domestic product, or the value of all goods and services produced in South Korea, probably shrank by a seasonally adjusted 2.7 percent in the fourth quarter of 2008 from the previous quarter, which would mark the biggest loss since early 1998.
They also forecast South Korea's export-dependent economy would barely avoid contraction but expand only 1.6 percent in all of this year, slower than the central bank's forecast for 2 percent growth.
Customs agency data released on Tuesday showed South Korean exports to China fell a record 35.4 percent in December over a year earlier and shipments to the European Union region dropped by 34.3 percent as the global recession deepened.
The bleak outlook on the economy underscored market expectations that the Bank of Korea would keep cutting interest rates, in addition to its reduction of the policy interest rate by a combined 2.75 percentage points over the past three months.
Under Tuesday's corporate restructuring plan, creditor banks said they would cut off their credit lines to shipbuilder C&Heavy and unlisted home builder Daejoo Construction, judging they were too weak to survive.
Builder Keangnam Enterprise and 13 other mostly small firms will be placed under creditors-led restructuring programmes because their troubles were deemed temporary, the creditors said in a joint statement.
The operation marks the first time in a decade that beleaguered firms in the country have been singled out for harsh restructuring after the government forced a number of weak ones to shut down in the wake of the 1997/98 Asian financial crisis. (Additional reporting by Seo Eun-kyung; editing by Jonathan Thatcher & Jan Dahinten)