SEOUL, SEPT. 18 -- The United States has asked South Korea for more than $450 million to support military forces in the Persian Gulf region, and the government here reportedly has agreed to provide about $150 million this year, according to local media accounts published today.

But Seoul officials denied that a decision had been made on the extent to which South Korea would back the U.S. buildup in Saudi Arabia that has followed Iraq's invasion of Kuwait.

They insisted that the issue is still being discussed by President Roh Tae Woo and his top aides.

Amid increasing calls on Capitol Hill for U.S. allies to allocate more money, Roh met here with U.S. Treasury Secretary Nicholas Brady on Sept. 7 to talk about South Korea's role in the buildup. At the time, U.S. and South Korean officials refused to say how much the United States was requesting from South Korea, a longtime ally that has relied for more than 40 years on U.S. troops for its security.

But South Korea's ambassador in Washington, Park Tong Jin, was quoted by local newspapers today as saying Brady requested more than $450 million for 1990-91.

In a separate report, the semiofficial Yonhap news agency quoted an unnamed official as saying a high-level meeting was held in Seoul today and a decision was made to provide about $150 million in cash and materiel this year.

With costs for the U.S. military buildup estimated at about $1 billion a month, Republicans and Democrats in Washington have called for Japan, West Germany and other allies to provide significant financial and logistical aid for the U.S. military and for countries such as Jordan, Egypt and Turkey, which are being hit by the United Nations' trade boycott of Iraq and occupied Kuwait.

After hesitating, Japan and West Germany have agreed to provide packages worth about $4 billion and $2 billion, respectively.

Officials here were surprised when the White House began seeking financial aid from South Korea, where the $5,000 per-capita income is far lower than in advanced countries.

The Korean economy has slowed from its 1986-1988 run of double-digit growth and massive trade surpluses, and Roh, a former general, could face trouble if he is perceived as ignoring domestic needs at the expense of the gulf crisis.

From Washington's perspective, South Korea is seen as a vigorous ally that has profited enormously from its longtime relationship with the United States.

It has taken in tens of billions of dollars in commercial loans since the 1960s, amassed considerable trade surpluses during the 1980s and been sheltered for more than 40 years under the U.S. defense umbrella, now represented by about 43,000 U.S. troops here.

The local reports disputed by the government said Brady asked Roh for $50 million in cash and $100 million in goods and services this year and $60 million in cash and $240 million in goods and services in 1991. Brady and other U.S. officials had made it clear that they would not request troops from South Korea because of the continuing threat from North Korea.

Like Japan, South Korea imports virtually all of its oil and depends heavily on shipments from the Middle East.