PHILIP ROTH spends much of his time in England these days. And after reading Blood Libels, one wonders if he has any secret literary kin in London, for Clive Sinclair's new novel, a weird and hysterical fantasy of Jewish life in Britain and Israel, derives much of its wildness from the early Roth.

That's not to say that Sinclair is a pale copy of his precursor. Even if he writes in his older American "brother's" shadow at times, he has created a brilliant, often terrifying work.

Sinclair -- who, incidentally, is not the famous British computer mogul but the author of a critical study of Isaac Bashevis Singer and his brother, Israel Joshua Singer, and the literary editor of Jewish Chronicle -- brings to life, in a very few pages, the astonishing character of Jacob Silkstone.

Jacob has all the sexual obsessions and attendant confusions of the young Portnoy. His family is kosher, and when he discovers that the German servant Helga is furtively feeding the Silkstones pork, Jacob exchanges silence for a hilarious sexual encounter in the bathroom. The master Roth would be proud.

The Silkstones attend a synagogue where the presiding figure is one "Rabbi Nathan who made Jeremiah the Prophet seem a forgiving sort. No one was spared his righteousness." Rabbi Nathan is an awful gasbag who flogs the congregation with booming, self-righteous sermons and whips young Jacob into shape for his bar-mitzvah.

The "big day" arrives, May 21, 1961, and Jacob sails through his Torah portion with ease. Dancing to the Rudy Rome Orchestra follows. Much eating of the ritual foodstuffs. In general, a fine time, reminiscent of the wedding in Goodbye Columbus.

During the party, however, Jacob slips off to the loo only to find the inebriated Rabbi Nathan trying to rape Helga in a stall. He is enraged at this awful scene of spiritual fraud. He does not soon forget it.

A dozen years later, Jacob writes a somewhat counter-Talmudic text, "Rabbi Nathan's Folly." Oy, the outrage of it! See if the following scene isn't reminiscent of the Zuckermans' chagrin at the publication of another horrific text in Roth's "Zuckerman Unbound":

"My parents were not amused.

" 'Are you satisfied?' asked my mother, pointing to an empty bottle of Valium, beside which was cast the offending manuscript, like a suicide note. 'Why don't you write something nice about the Jews,' she said, 'instead of dreck like this?'

" 'There are plenty of others to do that,' I said. 'Besides, you are confusing fact with fiction. I write stories.'

" 'So tell a story,' said my father, 'and don't make a laughing-stock of Rabbi Nathan.'

" 'Our son is well-named,' said my mother, 'his words are like silk, but his heart is a stone. He'll publish it, if he can. May his arm drop off.' " LET ME SAY that this is pretty much where the Portnoy Redux, or Zuckerman Rebounds, episodes end. The remaining 150 pages grow stranger and stranger, a dark study in Jewish fears and fates.

For reasons that are too elaborate to explain here, Jacob's early novel and his obsessive personality, in general, are the seeming cause of awful events: the assassination of a friend named Uzi, the death of a lover, the Israeli invasion of Lebanon, the coma of his son.

In addition to the bizarre texture of fantasy here, Sinclair's novel can also be read with interest for its political slant, its dramatic screed against Ariel Sharon and the militaristic right-wing of Israeli politics.

At one point Sinclair's fictional Sharon and some army men burst into an apartment where Jacob is having seder dinner with his Israeli lover, Hannah, her husband and children. With a gun in his hand, Sharon says:

"You make me sick, you Jews who aren't prepared to pay the price for freedom. What, you think the terrorists will go away if we say nice things to them? I had the bastards at my mercy -- I was just waiting for the word to go into West Beirut and exterminate the lot. But it never came. Instead I had to tell my men: 'Stop. We must let the murderers of our children go.' Because a few of my fellow citizens got cold feet."

Sinclair's sympathies, I think, are with the cuckolded husband who has become an active member of Peace Now.

The final chapter, in which Jacob tries to discover whether he was adopted or born a Jew, is a scene of apocalyptic, anti-Semitic terror in which Golders Green and other areas of London are invaded by storm troopers. Dozens of Jews are murdered and synagogues are destroyed. Then, "As if the pogroms in England were his cue, Dom Arov Sharon finally seizes power in Israel with extraordinary ease; no one, it seems, has the will to stop him."

Blood Libels, which begins with all the pained charm of the early Roth, ends with even more darkness than The Prague Orgy. The fires of an English Jew's paranoia are fueled by fantastic murders, the ghosts of martyred Jews aboard El Al airliners and the fear that Israel's national attitude has crossed the line from vigilance to brutality. All this makes for a novel of unusual ambition, both as politics and as fantasy.

Where Blood Libels does seem to fall short is in its brevity. This book carries the reader from Jacob's childhood to his agonies in London to his education in Israel, and any number of possibilities which fulminate from Sinclair's imagination begin, trail off and are never heard from again. Sinclair means to be swift, but sometimes he seems too much so. Even some of the writing seems haphazard, too reliant on speeches and a bit dashed off.

It is because of the richness of Sinclair's story and the riskiness of his themes that the reader, perhaps greedily, often asks for more. Despite those faults, Blood Libels is a raw, stunning piece of work and Clive Sinclair is a novelist, a decidedly Jewish novelist, who is bound to astonish his readers.

David Remnick is a staff writer for the Style section of The Washington Post.