The gates of the Katowice steel mill, the largest and most prestigious industrial plant in Poland, were plastered today with huge banners proclaiming "Strike Unto Victory" and slogans denouncing the declaration of martial law.

Inside, leaders of a 15-man strike committee claimed to have the support of most of the plants' 19,600 workers in defying the newly established military council. They said they would reject a deadline of 2 p.m. local time to vacate the premises, despite the fact that Army units were known to have been moved up to a forest nearby.

Reports from around the rest of the country are sketchy, but along a 300-mile corridor from the Czechoslovak border to the Polish capital, there was evidence yesterday that Solidarity's call for a general strike was attracting at least partial support.

The picture that emerged was of workers staging strikes at the big enterprises, including several mines, while public transportation and shops functioned normally for the most part.

The military presence in the area appeared relatively muted, apart from a convoy of 20 tanks moving toward Warsaw and Army movements near the Katowice steel mill.

In Katowice, an industrial center in southern Poland, police had occupied Solidarity regional headquarters, although the building remained decorated with posters and Polish flags. Outside, Solidary activists said that 55 of the 60 members of the union's regional board had been arrested.

They claimed that about 2,000 other factory representatives of Solidarity in the region had also been detained by police. Although that figure is impossible to confirm, if it is even approximately accurate, the total number of arrests in Poland must run into tens of thousands, though this figure is impossible to confirm.

The scene there also revealed what could emerge as a significant political battleground with young male workers largely expressing continued support for Solidarity and harassed housewives wishing a speedy return to normality. Several people said the government's intensive propaganda campaign had succeeded in frightening the population into accepting -- but not welcoming -- the new measures.

Two large gasoline trucks were drawn up across the entrance of the steel mill, but the strike committee issued a proclamation appealing to workers to use only passive resistance if the plant was occupied by the Army.

The committee chairman, Antoni Kusznier, said that in that case an "Italian strike" would be called -- under which strikers would go through the motions of work without producing anything. Kusznier, who could face a heavy sentence under martial law for organizing a strike, said he was the only member of the Solidarity union's nine-man inner management group at the factory who escaped arrest in police swoops on Sunday morning.

The strikers described their demands as the release of all detained Solidarity activists and the end of a communications blockade that has totally undermined the union's once highly efficient information network.

Despite the blockade and restrictions on travel, some information was still being passed from factory to factory by couriers. Kusznier acknowledged that the Army units probably could occupy the mill with minimal resistance from the work force, but he insisted it would be impossible to get production back to normal. Both of the foundry's giant furnaces have been shut down, he said.

"The Army are also Poles. They are the sons of the same workers as we. Will they shoot at me if I refuse to work?" he asked.

Kusznier's defiant attitude was not shared by a young housewife near the plant who was attempting to shop for her family despite long lines outside food stores. Asked if she supported the strike, she replied: "I don't support anybody -- except for my two children. I just want to live in peace."

Slogans affixed to the front of the plant attacked the Army, which until now has enjoyed relatively high popular support in Poland. Some read "Army Back to the Barracks," "Jaruzelski Traitor to the Workers," "We Don't Want Brotherly Help" and "Jaruzelski Came in a Russian Tank."

Despite the references to Soviet intervention, the strikers acknowledged that the presence of only Polish troops in imposing martial law was a major factor in dampening resistance.

The strikers printed a special strike bulletin at the factory, "Free Trade Unionist," which included reports of industrial action elsewhere in Poland. The Lenin Shipyard in Gdansk was reported to be the headquarters of a national strike committee and strikes were reported in half a dozen coal mines in Silesa.

In addition to the strike activity at Katowice, there was evidence of a strike in progress at the Jastrzembie Manifest Lipcowy coal mine. Now, as in the August 1980 Solidarity activity, strikers said they had set up an interfactory strike committee to represent several mines in the region.

A strike was also in progress at the Myslowice coal mine near Katowice, but the nearby Sosnowiec mine appeared to be working normally.