WASHINGTON-U. S. Capitol police-assisted by members of the Metropolitan Police Civil Disturbance Unit (CDU)-arrested more than 1200 hold-over antiwar demonstrators here yesterday over the stringent objections of four members of Congress.

At the request of Rep. Bella S. Abzug (D-N. Y.), Capitol police chief J. M. Powell pulled back a line of police barring demonstrators from the Capitol building at 1:45 p. m., and protestors poured onto the east steps of the House wing, chanting and singing antiwar verses.

However, Powell reversed himself 30 minutes later and ordered the CDU to begin arresting the 1200 demonstrators blanketing the Capitol steps. Those arrested are charged with illegal assembly on the Capitol grounds, which carries a penalty of up to $500 and six months' imprisonment.

Abzug-who had invited the demonstrators onto the grounds to present the People's Peace Treaty to her and three other Congressmen-immediately accosted Powell and demanded that he stop the arrests and release the persons who were being loaded into a fleet of police buses.

But Powell ignored Abzug's protests-as well as those of Representatives Ronald D. Dellums (D-Calif.), Perren J. Mitchell (R-Md.), and Charles B. Rangel (D-N. Y.)-and CDU police in riot gear continued to clear the steps for three-and-one-half hours.

Powell ordered the arrests after consulting with House Sergeant-at-Arms Zeake W. Johnson Jr., and with House Speaker Carl Albert (D-Ckla.). Both, he said, agreed with his belief that the demonstrators were "disorderly and disruptive."

Powell told Abzug and the other Representatives that their invitation to the demonstrators was invalid because they had not obtained permission for the assembly from the Capitol police.

"Perhaps inadvertently the Congressmen encouraged illegal acts," Powell said. Dellums disagreed, terming the police's action "fascist."

Dellums also said that he, Abzug, Mitchell and Rangel did not hear any of the 12 warnings which Powell said he issued for demonstrators to clear the Capitol steps or face arrest.

Demonstrators danced, sang, and chanted as the police cleared the steps one at a time. One man removed his clothes and stood facing a crowd of about 1000 who watched the sweep from behind police lines.

After police finished clearing the steps and began to withdraw at 6 p. m., about 250 spectators rushed across a short expanse of driveway and sat down on the steps.

Police thereupon turned around and resumedtheir arrests, clearing the Capitol grounds for the remainder of the day.

Demonstrators offered no resistance; many went limp when confronted by police. The CDU dragged at least 40 down the steep concrete steps after holding them up by their collars to photograph them.

The Capitol sit-in followed a short march from the Mall on the west side of the building, where Mayday organizers held a "People's Press Conference" for the second straight day.

At the same time over 500 members of a group calling itself the Federal Government Employees Against the War began a three-hour rally in Lafayette Park opposite the White House and listened to Representative Paul N. McCloskey (R-Calif.) and others denounce President Nixon's handling of the war.