Britain was pitted against the continent today in a rage over money and democratic voting principle that threatens to scar relations within the European Community for months.

"The European Community is now at a major turning point," declared the Financial Times of London.

"Europe shaken," said the conservative Le Figaro in Paris. Belgium's Le Soir warned of damaging consequences that British retaliation could have. Observed the Frankfurter Rundschau somewhat nervously from West Germany, "The consequences cannot be predicted."

Passage Tuesday of European farm price increases over a British veto broke 16 years of rule by unanimity and dealt what British officials regarded as the third blow against them this week.

Monday night Europe's ban on Argentine imports was extended in shorter and shakier form than when it began a month ago, and it came on top of Britain's anger over being denied the full refund it wants from the community budget.

Because of the Falklands crisis, British Prime Minister Margaret Thatcher is expected to wait to respond to the slap her European partners delivered. A senior British aide told The Washington Post's London correspondent, Leonard Downie Jr., today that two options had been ruled out:

One was withdrawal from the community, which Britain joined nine years ago and which provides a number of trade advantages. The other was an "empty-chair" approach, meaning a British boycott of community meetings.

Most likely, Thatcher's aide said, the British government will decide to withhold payments to the European Community--an unprecedented move that would subject Britain to legal action from the other nine members.

Meantime, French President Francois Mitterrand, showing no regret for the farm vote that reportedly caught Thatcher by surprise, said in Algiers that when he visited Thatcher in London Monday, he left "no doubt about France's determination" on the farm price issue.

But Thatcher's aide said no European head of government had warned the prime minister of the others' intention to force the price increases through.

The reason that the partners would roll over Britain during its Falklands crisis seemed mostly the result of a loss of patience. Britain had been blocking the 10.7 percent rise in farm prices as leverage to secure an acceptable rebate for excessive payments to the community. But other members are not inclined to refund as much as Britain wants, and they were under strong pressure from farm lobbies at home to pass the increase.

"When a country chooses force and blackmail, we cannot be surprised if others respond as best they can," said Italy's agriculture minister, Giuseppe Bartolomei.

West German officials, whose government would bear much of the extra cost of relieving Britain, were embittered by what was seen here as Britain's intransigence during months of negotiations on the budget issue.

Britain ends up paying much more to the community than it draws because payments and receipts are figured on different bases. Payments into the community are keyed to value-added-tax receipts, derived from products and services at each stage of production or distribution. Payments from it go largely to subsidize farmers, but Britain's agricultural sector is relatively small.

The community's return to majority voting may still be turned to British advantage. Mitterrand tried to reassert that the old unanimity principle--effected by former French president Charles de Gaulle after a six-month boycott of the community in 1965--could still be invoked by a member "when it's really a matter of vital interest."

Said Thatcher's aide on the demise of the old rule, "They will live to regret this. They will rue the day they did this because they, too, will each find the need sometime in the future to protect their national interests."