Oct 6 (Reuters) - Delek US Holdings ( DK ) has sued

London-based Marex Group ( MRX ) and Texas-based BTX Energy,

accusing them of supplying contaminated crude oil that damaged

one of its U.S. refineries and caused more than $30 million in

losses.

In a Texas district court filing, Delek said it began buying

crude from Pinnacle Fuel in January, with deliveries handled

through BTX Energy's terminal in Winnie, Texas.

By February, Delek detected unusually high levels of organic

chlorides in its Heavy Naphtha Hydrotreater unit, according to

the complaint.

Tests showed chloride concentrations as high as 5,668 parts

per million, nearly 1,000 times above contractual limits, which

Delek says damaged refinery units, forced lower processing

rates, and contaminated about 300,000 barrels of clean oil.

Marex ( MRX ), which acted as the guarantor of Pinnacle's supply

contract, has filed a petition to move the case from the

Chambers County district court to federal court.

Marex ( MRX ) and BTX Energy did not immediately respond to requests

for comment.