LONDON (AP) _ Lord George-Brown, a man of recognized brilliance who became Britain's foreign secretary and might have been prime minister but for his explosive nature, is dead at 70, his family announced Monday.

George-Brown, who was born George Brown and inserted the hyphen when he was made a baron, died Sunday of complications from surgery to correct severe internal hemorrhaging, said his brother, Ronald Brown. The surgery was performed last week at a hospital near his home in Cornwall.

The harsh-tongued and unpredictable George-Brown, son of a truck driver, was seen by some as a brilliant statesman and by others as a disaster.

As Labor Party foreign secretary from 1966 to 1968, under Prime Minister Harold Wilson, his blustery, outspoken style often seemed at odds with British diplomatic tradition.

He was involved in British attempts to mediate peace in Vietnam, however, and was an author of U.N. Security Council resolution 242, which was adopted in November 1967 and still is the cornerstone of Middle East peacemaking efforts. It calls for Arab recognition of Israel's right to exist in exchange for its withdrawal from occupied territories.

George Brown was born Sept. 2, 1914, and raised in a poor tenement in south London.

He was made a peer after losing his seat in Parliament in 1970. As to the ennoblement, he told an interviewer at the time: ''It's ridiculous to give me that stupid title. I'm not a lord and I wish I could drop the damn thing.''

As the 1970s progressed, he grew disillusioned with the labor movement, alarmed at what he considered the absence of democracy in the trade unions. He resigned from the Labor Party In 1976.

''This is the saddest night of my life,'' he said. ''After 45 years I've left for the same bloody reasons I joined.''

He joined the centrist Social Democrats when the party was founded in 1981.

Brown entered politics after working as a sales clerk and attending night school. From a trade union job he was elected to Parliament for the Labor Party in 1945. He rose to deputy leader of the party under Hugh Gaitskell and acting leader when Gaitskell died in 1963.

He could have been prime minister if Wilson had not defeated him for the party leadership. Many regarded him as the best man in the party, but worried about his unpredictable conduct and his drinking, which was sometimes heavy.

The public loved Brown. His public exploits, and shouting matches with his colleagues and adversaries, seemed as much a part of the ''swinging London'' of the 1960s as the Beatles and Wilson's vision of a new Britain based on science and freed of ancient class distinctions.

He resigned as foreign secretary in 1968, saying Wilson failed to consult him on a gold crisis, and lost his seat in Parliament two years later.

As he left Labor headquarters after resigning his party membership in 1976, he slipped and fell into a gutter in front of photographers. ''OUT and DOWN 3/8'' said a newspaper headline. George-Brown blamed the fall on his new bifocals.

''I'm no saint, and there were hard drinkers in my family,'' he said in a newspaper interview in 1977. ''Of course, I've sometimes woken up next morning and thought, damn 3/8 Of course I've sometimes wished I'd kept my mouth shut at dinner.''

His public image continued to be dogged by controversy. He had two convictions for drunken driving, and left his wife Sophie in 1982 after a 45- year marriage that produced two daughters.

Labor's foreign affairs spokesman, Denis Healey, told a television interviewer Monday: ''He lacked a degree of self-discipline that would have taken him straight to the top.''

Wilson said: ''At his best George was a markedly successful parliamentarian. His off moments saddened his colleagues and Conservative opponents alike.''