Statements by Prime Minister Margaret Thatcher and her new minister for Northern Ireland after this week's Anglo-Irish summit have shattered what was described as the "positive" mood of the meeting, Irish officials here and in Dublin said today.

The Irish officials said the mood in their government is "so despondent" and there is such "great disappointment" with Thatcher, that it casts doubt on the wisdom of another summit early next year between Thatcher and Irish Prime Minister Garret FitzGerald.

In a communique following the meeting at Chequers, the prime minister's estate outside London, Sunday and Monday, both leaders agreed to aim for "a further meeting . . . within the coming months."

However, at a press conference here immediately after the summit, Thatcher, under questioning, flatly rejected the three major models, or options, for some new form of joint authority in British-ruled Northern Ireland that had been proposed by the New Ireland Forum in May.

Irish officials said that Thatcher's remarks were maddening because the private talks between the two leaders had gone rather well in seeking to find some new common ground for dealing with the continuing sectarian violence in Northern Ireland and for easing political tensions there.

While it was known in Dublin that the British would not agree to any change in the north's status without approval from the the province's Protestant majority, which is loyal to Britain, the emphatic tone in which Thatcher rejected the forum's suggestions has caused great political embarrassment for FitzGerald, a prime mover behind the report, the officials said. The Irish leader has taken risks at home by seeking greater cooperation with Britain.

Irish officials confirm that in an angry meeting in Dublin of his Fine Gael party after the summit, FitzGerald accused Thatcher of being "gratuitously offensive" in her press conference comments about the New Ireland Forum report.

In the British Parliament today, Thatcher told questioners she was "in total disagreement" with the remarks of FitzGerald as reported. She said, "I do not understand his comment in any way."

The Irish prime minister was clearly uncomfortable at his own press conference immediately after Thatcher's Monday and declined to answer reporter's questions about Thatcher's remarks.

The Irish foreign minister, Peter Barry, is reported to have described Thatcher's behavior as disgraceful.

The officials also said that comments by Thatcher at her press conference and by British minister Douglas Hurd at a press conference in Northern Ireland yesterday casting doubt on the "alienation" of the Catholic minority in the north also were resented.

The third factor that has added to the dismay in Dublin is Thatcher's insistence at her press conference that Britain cannot impose any solution in Northern Ireland and that only the people of Ulster can make any agreement work.

The Irish maintain that it is virtually impossible for the forces of political confrontation in the north to come together on their own and that there must be some outside pressure for reconciliation.

Aside from concern within his own party, FitzGerald was also subject to a sharp attack in Parliament from opposition leader Charles Haughey, who accused him of "abject capitulation to a new British intransigence and a craven desertion of the principles of the New Ireland Forum report."

The dilemma for London is that while the forum report is viewed as unrealistic because the two-thirds Protestant majority in Northern Ireland would not agree to any form of control by a Catholic government of Ireland, it represents, at least in spirit, the most well-intentioned effort thus far to find some peaceful solution.

The report was prepared by the three main moderate Catholic parties in Ireland and the moderate Catholic minority party in the north, and it was viewed as the best way to keep the outlawed Irish Republican Army from becoming the main voice representing the Catholics of the north.

In his press conference, Hurd also ruled out any chance of Dublin exercising joint executive authority in the north. The Irish are known to be interested in some form of a low-key consultative role, and such formulas are believed to have been discussed by Thatcher and FitzGerald.

Hurd's comments also provoked a row. Irish Deputy Prime Minister Dick Spring said it was "astonishing and unacceptable" for Hurd to have talked publicly and selectively of some of the issues discussed during the supposedly confidential summit.

Today, however, Spring said, "I think now it is our duty as a government to try to retrieve that situation and make progress."

The subdued mood in Dublin after the summit also reflects what has become a somewhat frequent problem for Thatcher. While she is often praised for stating her views and policies forthrightly to avoid any misunderstanding, she also has suffered from appearing to be insensitive in so doing.

In recent months, she has suffered sharp setbacks by Britain's conservative House of Lords for the way in which she sought to abolish local government councils rather than for the policy itself.