June 6 (Reuters) - Missouri authorities are

investigating a fake press release about the damaging livestock

pest New World screwworm that sparked a selloff in U.S. cattle

futures markets last week, the state's agriculture department

said on Friday.

U.S. agriculture officials and farmers are on high alert for

screwworm as it has moved north in Mexico from Central America,

arriving within about 700 miles (1,125 km) of the Texas border.

The U.S. Department of Agriculture indefinitely halted U.S.

cattle imports from Mexico last month in a bid to keep out the

parasite, which eats livestock and other wild animals alive.

Screwworm infestations can kill cattle if left untreated and

make them susceptible to secondary infections.

On May 27, a false press release was sent to a northwest

Missouri radio station about screwworm, the Missouri Department

of Agriculture said.

A report on the radio station's website pressured Chicago

Mercantile Exchange cattle futures before being taken offline,

livestock traders said. Live cattle futures fell nearly

2% before paring losses, as daily trading volumes in the market

spiked 77% from a week earlier.

The Missouri State Highway Patrol's Rural Crimes Investigative

Unit, the Livestock and Farm Protection Task Force, and state

attorney general are investigating the matter, Missouri's

agriculture department said in a press release.

State officials want to determine "if this was an act with

malicious intent to cause panic in agricultural markets," the

department added.

U.S. cattle producers' group R-CALF USA last week asked the

Commodity Futures Trading Commission, which regulates futures

markets, to investigate.

The commission did not immediately respond to a request for

comment, and exchange operator CME Group ( CME ) declined to

comment.