LONDON — The number of people who said they were sexually assaulted by Jimmy Savile, one of Britain’s most popular television hosts, expanded to 300 from 200 in just the last week, and other people may have acted with him, the Scotland Yard officer heading the investigation said Thursday.

The officer, Cmdr. Peter Spindler, described Mr. Savile, who died last October at 84, as “undoubtedly” one of the most prolific sex offenders in recent British history, during a 50-year career as a self-styled pied piper for the young, the sick and the lonely. Commander Spindler said that in preliminary telephone interviews with 130 of the potential victims, 114 of them had accused Mr. Savile of criminal behavior ranging from “inappropriate touching” to rape. Of the 300 complainants, he said, all but 2 have been female.

Commander Spindler said the “vast majority” of the accusations logged by the police were against Mr. Savile alone, with the remainder involving Mr. Savile and others or episodes in which the entertainer was not implicated. Although the commander specified that investigators had found no evidence of a “pedophile ring,” as some published accounts in Britain have suggested, he said that a number of “living people” were under investigation.

Later, an article on the BBC’s news Web site quoted “sources close to Scotland Yard,” whom it did not further identify, as saying the police were looking at some “figures of high standing” who might have helped Mr. Savile. “It is thought investigations are looking at those who may have assisted Savile, helped organize abuse, cover it up or taken part in assaults themselves,” the BBC story said.