Seoul stocks give up gains; Samsung Sec slides

(Updates to midday)

SEOUL, Feb 26 (Reuters) - Seoul stocks gave up most of their
early gains to trade up just 0.2 percent on Tuesday, retreating
from a five-week high, as Samsung Securities dived on prosecutor
plans to probe it as part of an investigation into Samsung Group.

Early in the session, the index rose 1 percent to touch its
highest level since Jan 18 as steelmakers led by POSCO bounced
after China-based Baosteel's price hikes raised bets regional
peers would soon follow suit.

The Korea Composite Stock Price Index was 0.19
percent higher at 1,712.32 points as of 0240 GMT, after rising as
far as 1,726.47 points during the morning.

Samsung Securities Co (016360.KS: Quote, Profile, Research, Stock Buzz) fell 4.43 percent to 66,800
won after the financial regulator said it would cooperate with a
prosecutors' plan to probe the brokerage as part of their ongoing
investigation into the country's top business group.

But POSCO (005490.KS: Quote, Profile, Research, Stock Buzz), the world's fourth-largest
steelmaker, rose 3.89 percent to 534,000 won.

(Reporting by Kim Soyoung; Editing by Keiron Henderson)