Amid signs of renewed social unrest, substantial price increases went into effect in Poland today, accompanied by limited government attempts to cushion the blow for this suffering nation.

Spot checks at a number of Warsaw stores found customers complaining bitterly about the sharp price hikes--topping 400 percent on some items--which are said to be necessary to bring prices into line with costs and set the basis for more thorough economic reform.

But the anger in this capital remained restrained for now.

A clash Saturday between police and mostly young demonstrators in the Baltic port city of Gdansk was blamed today by the official press on U.S. provocation and linked to what was described as America's anti-Poland propaganda campaign.

Authorities claimed to have swiftly reimposed a harsh form of order in Gdansk, a stronghold of militant trade union activity, no doubt with the idea of setting an example of the brutal consequences that other violations of Poland's martial law rules could expect.

Faced with adjusting to the biggest round of price increases in the country's postwar history, one woman today called the situation "criminal" as she swept out of a meat shop on Koszykowa Street. On the second floor of the Delikatesy food store on Marszalkowska Street, three other women complained that in Hungary, at least, when the prices began going up some years ago, they rose gradually so people could still afford things.

In the Centrum department store in downtown Warsaw, a floor manager was asked for her personal reaction to the price increases, which apply to basic food items, energy supplies and consumer goods. She made a motion with her hand as though her throat were being cut.

Among the larger increases put into effect today were those for sugar, which rose from 17 cents to 57 cents a pound, and butter, which went from 42 cents to $1.50. Ham now costs 4 1/2 times the previous price, and herring and cod prices multiplied by 2 1/2 to 4 times.

Storekeepers reported that the size of crowds and level of buying today was normal for a Monday. Open opposition to the increases had not been expected today under the force of martial law. The full bite out of average incomes is not likely to be felt until later in the month.

Trying to alleviate the impact, officials announced that savings accounts would be automatically boosted by 20 percent, along with incomes, which already were slated to go up on average by the same amount. This was described as an additional form of compensation for the price increases and also as a kind of "bonus" for those who keep savings accounts.

But the new payments are still small in relation to some of the price rises and, more frustratingly, will be made not in the form of readily available cash but as interest-bearing deposit bonds redeemable three years from today.

The government also issued an expanded list of goods that will fall under state regulation in what was portrayed as a move to rein in producers who were said to have pushed up their prices too high since the first of the year when higher prices for their raw materials came into force.

The new regulated price list covers many basic products from clothing and toiletries to home furnishings and toys. It comes in addition to a list of official prices covering food, energy, public transport, medicines and teaching aids.

In effect, the added items allow the authorities to provide lesser quality consumer goods cheaply, while keeping higher quality goods still subject to market forces. "Everyone will at least be able to dress gray," said one Polish journalist.

Independent corroboration, meanwhile, of the weekend battle in Gdansk--reported last night to have left six civilians and eight police officers hurt and 205 people in detention--was frustrated today by the shutoff of phone and telex links between Polish cities and by the restrictions on travel still in effect here.

Foreign correspondents were officially advised today that they would be free to travel and report throughout the country--except military installations--and were handed special blue passes. The move was explained by Foreign Ministry press officials as another sign of the beginning of relaxation of martial-law conditions.

But there was a catch. Visits to outlying areas still depend on the willingness of territorial authorities to welcome Western reporters, and requests for such visits must be made in writing.

Although disclosed only today, the order for the seeming relaxation of press restrictions was signed by Gen. Wojciech Jaruzelski, the Polish leader, on Jan. 12. This would suggest that the authorities have something of a formal plan for the gradual lifting of martial law.

A number of other bans have been lifted in recent days, including those on certain kinds of private gatherings and on the publication of regional papers. Beginning Feb. 10, intercity phone and telex communications are scheduled to be restored and international phone calls will become possible through Polish operators.

Authorities have indicated their intention to restore more civil liberties by the end of this month if there are no more disturbances.

But the situation in Gdansk showed what could happen if protests persist. There, a curfew has been extended from 8 p.m. until 5 a.m.; phone lines in the city have been turned off again, and the use of private vehicles is now banned. Migration and registration rules were also tightened during the weekend.

Commenting on the demonstration, the main Communist Party paper, Trybuna Ludu, blamed it on "opponents of Poland" who were "still trying to stir up unrest and destroy order, which is being restored with so much difficulty."

"It is not by accident that the street demonstration in Gdansk coincided with the so-called Solidarity Day with the Polish nation, proclaimed in the United States, being the climax of a sharp propaganda campaign directed against Poland," the party daily said.

The official Polish press today carried critical commentaries on the American television special on the Polish crisis yesterday. The Polish press agency described it as an "obvious interference in Poland's internal affairs." The agency's Washington correspondent said the show had proved "a downright fiasco" in view of "its negligible influence in the United States" and a "complete debacle" in Europe.