The Sunday Mirror accused him of being a pervert....however the allegations were never proven.

the following is from the Irish Examiner:

Child sex file could
close on sci-fi writer

SRI LANKA will close its investigation of science fiction writer Sir Arthur C Clarke unless a British newspaper hands over evidence to support its allegation that he was a paedophile, a government official said yesterday.
Police sought the tape recording of an interview conducted by the Sunday Mirror on which it based its allegation that Sir Arthur had sex with children, but the paper had not responded to repeated requests, said CR De Silva, the Sri Lankan government additional solicitor-general.
"We have approached Interpol. Our embassy in London did its best. In short, we did everything, but the tape has not come," de Silva said.
"Our investigations in Sri Lanka have not found any evidence against him.
"Keeping this in view, and the situation that we are unable to get the tape, we will have no option but to close the case," he said.
Sir Arthur's office said his lawyers were discussing with government officials how to close the file.
He has strenuously denied the allegations made against him.
The Sunday Mirror published its story in February, a few days before the 80-year-old writer was to be knighted by the Prince of Wales who was visiting Sri Lanka at that time. The ceremony was postponed at Sir Arthur's request.
Police questioned the author and three of the four men quoted by the British tabloid newspaper as having claimed to have had sex or discussed sex with him.
Sri Lanka asked Interpol in April to get the interview tape from the newspaper. A reminder was sent a month later. The Sri Lankan High Commission in London also attempted to get the tape from the Sunday Mirror.