The progressive Uri Party, which supports Roh's reformist progra-mme, won between 155 and 182 seats in the 299-seat chamber, according to exit polls conducted by television networks.

The victory is expected to help Roh survive his impeachment ordeal, strengthen his drive for reconciliation with North Korea and bolster his demand for a more equal relationship with the United States.

The conservative Grand National Party (GNP), which controlled the outgoing National Assembly with 137 seats, won between 92 and 115 seats, the exit polls conducted by the country's three major networks said.

The outcome was a dramatic victory for the Uri Party, which was formed only five months ago and held just 49 seats in the outgoing chamber.

But it was less of a rout than conservatives in the GNP had feared from an electorate angered at the impeachment of the president last month.

The result also signalled an abrupt shift to the left for South Korean politics, marking the first time in over four decades that the country's parliament has been controlled by reformist legislators.

"If exits polls are true, people have rescued our democracy through these elections. They have saved the president. The elections confirm the people are the owner of this country," said Uri Party leader Chung Dong-Young. Official results are not expected for several hours.

The March 12 impeachment of Roh was the single key issue in the contest. Roh, though not a member of the party, said he would resign from office if it fared poorly in the polls.

The Uri Party asked the public to punish the GNP for leading the vote which was opposed by seven out of 10 South Koreans.