SEOUL (Reuters) -The U.S. has agreed to allow South Koreans to work to set up facilities at U.S. investment sites under existing temporary visas and open new channels to help its ally send workers to do business there, Seoul's foreign ministry said on Wednesday.

But U.S. officials at a working group meeting offered no new answers to South Korea's argument for a wider access to U.S. visas for specialty workers despite reaffirming a commitment to advance trade and investment partnership, the ministry said.

The U.S. side made up of Departments of State, Homeland Security and Commerce officials made clear South Korean workers can work to install, service and repair equipment needed as part of South Korean business investment in the U.S., it said.

A new section dedicated for visas related to South Korean businesses will be set up at the U.S. embassy in Seoul and U.S. immigration authorities will open a new channel with South Korean missions to better coordinate visa matters, according to the foreign ministry.

The working group was set up in the aftermath of a massive immigration raid at a Hyundai Motor ( HYMLF ) car battery facility under construction in the U.S. state of Georgia in September where hundreds of South Korean workers were arrested.

The arrests, which stunned the South Korean government and public, highlighted the lack of access to the right class of U.S. visas for specialised South Korean workers needed at investment sites.

The U.S. officials said a more fundamental change to U.S. visa systems to accommodate Seoul's demand for clearer and certain access for its specialty workers faced "practical legislative constraints," the South Korean ministry said.

South Korea has pushed for years for a bill that would create or expand visa categories to accommodate skilled South Korean nationals who need to visit the United States.

That bill has had difficulty getting through Congress because visas are linked to immigration, one of the most sensitive subjects in the United States, according to South Korea's foreign ministry.

U.S. Deputy Secretary of State Christopher Landau stressed the "critical role" of the skilled workers of South Korean companies investing in the U.S. at the group's first meeting in Washington, the State Department separately said.

The U.S. was committed to encouraging investment by companies from South Korea as one of the leading foreign investors in the country, it said in a statement.

The working group will hold further meetings, South Korea's foreign ministry said.

(Reporting by Jack Kim; Editing by Jamie Freed and Lincoln Feast.)