Steel importers charged today that sharp increases in the minimum prices the government sets for foreign-made steel have virtually eliminated any price competition between domestic and foreign steel on more than half of the steel imported into the United States.

Kurt Orban, president of the American Insitute for Imported Steel, said that after the next increase in the so-called trigger price mechanism goes into effect Jan. 1 there will be no price differential at all on five major product categories that account for 60 percent of all steel shipped to the United States from abroad.

Among them are hot-rolled and cold-rolled sheets used in such basic consumer products as cars and appliances.

Orban said it is time for the U.S. government to scrap the trigger prices.

He said at a press conference that since the trigger prices went into effect last May, the U.S. steel makers have been operating at close to full capacity and have been making large profits.

While steel importers complain of the chilling effects of the trigger prices on their orders, domestic steel makers complain that the trigger-price mechanism is not working. Foreign shipments of steel to the United States are higher this year than in 1977. Many major steel companies have said that unless imports slow soon, they will return to filing complicated antidumping cases at the Treasury Department alleging that foreign producers are selling their steel here below cost.

The trigger-price mechanism is supposed to be a substitute for the laborious process of filing antidumping suits. Orban said that "in view of the significant improvement of domestic profitability and capacity utilization, the continuing complaints about large import tonnages are hardly realistic."

He also charged that the trigger prices had added a significant boost to domestic inflation. Domestic steel makers have raised their prices substantially this year, in large part because trigger prices have forced up the price at which much foreign-made steel can be sold in the United States.

Last month, the Treasury announced a 7 percent increase in basic trigger prices, mostly reflecting the sharp decline in the value of the dollar vis a vis the Japanese yen.