Penny-stock king Meyer Blinder, whose brokerage activities are under fire across the country, was hit yesterday with a $20 million civil action by the Securities and Exchange Commission.

The SEC charged that from June 1985 to February 1987, Meyer Blinder and his firms Blinder, Robinson & Co. and Intercontinental Enterprises Inc. "engaged in an unlawful scheme to mislead and defraud Blinder Robinson's customers in connection with the sale of more than 1 billion 'penny stock' shares of 12 shell companies."

A shell company generally is a firm without any established business.

The SEC charged that the Blinder firms made more than $20 million in profits by using high-pressure sales tactics and charging customers excessive markups, which ranged as high as 140 percent over the prevailing market prices. Normally, any undisclosed markup over 10 percent is illegal, the SEC said.

The SEC asked the court to make Blinder and his companies "disgorge any and all ill-gotten gains" resulting from the alleged practices.

Earlier this year, Blinder and others were indicted in Las Vegas on federal racketeering and securities fraud charges. The indictments seek a forfeiture of $9.5 million.

Blinder could not be reached for comment late yesterday. Blinder Robinson general counsel Kalmon Glovin told the Associated Press the lawsuit appeared to be a ''rehashing of old allegations by the SEC, which Blinder Robinson ... and Meyer Blinder have been and are being vigorously defended against in other litigation.''

Meanwhile, the SEC voted to ask for public comment on a plan that would tighten control over the investments that money market funds make in commercial paper, a form of short-term corporate IOUs. Gene Gohlke, acting director of the division of investment management, said the proposals are intended to spur money market funds to buy less risky commercial paper and to encourage the funds to put their money in a wider selection of paper.

The SEC also said it would seek public comment on a proposal to help the commission foresee potential financial problems at brokerage firms.

Under the plan, holding companies of brokerage firms would have to give the SEC two days' notice before they could withdraw large amounts of excess capital from their brokerages.

This is the money brokerage firms maintain above a minimum level to protect investors. The SEC also would be given the authority to temporarily prevent the holding companies from making those withdrawals.