A federal judge in Dallas yesterday halted for 10 days a federal investigation of the silver trading activities of the billionaire Hunt family of Texas.

U.S. District Court Judge Robert Porter issued a temporary restraining order that had been requested by attorneys representing six members of the Hunt family.

The order prevents the Securities and Exchange Commission from questioning Nelson Bunker Hunt and William Herbert Hunt about their silver purchases and their business dealings with a group of banks, brokerage houses and precious-metals dealers.

The SEC is investigating possible securities fraud and other violations of federal laws by members of the Hunt family during a silver-buying spree that preceeded the collapse of the silver market last year.

The SEC had ordered Bunker Hunt to come to Washington tomorrow for three days of questioning and had subpoened his brother Herbert to give a deposition next week.

The restraining order is only temporary. After reviewing additional arguments in the case, Porter is to decide next week whether to extend the ruling or let the SEC resume its investigation.

Since a few days after the silver market hit bottom on March 27, 1980, a team of SEC investigators has been conducting the most far-reaching investigation ever of the finances of the secretive Texas billionaries.

The Hunts had cooperated with the investigation until about a month ago.