Doctor Who is a 'ludicrous' show with 'pixel thin' science fiction, according to Terry Pratchett, the author of the best-selling Discworld fantasy book series.
Creators of the hit BBC series were guilty of scripts full of "fast talking, and what appears to be that wonderful element 'makeitupasyougalongeum' ", he told the magazine SFX.
Writing as the science fiction magazine's guest editor, he admitted: "I wish I could hate Doctor Who."
Although he said he was still "a believer" in the show, which regularly pulls in more than eight million viewers, he had recently "noticed something".
"It's this; Doctor Who is ludicrous and it breaks most of the laws of narrative."
Episodes were plagued by "the unexpected, unadvertised solution which kisses is all better," he said.
While "a decent detective story" provided viewers with "enough tantalising information to allow you to make a stab at a solution" he said, "Doctor Who replaces this with speed, fast talking and what appears to be that wonderful element 'makeitupasyougalongeum'.
Pratchett, whose make-believe Discworld is perched rather implausibly on the back of four elephants, said he wished Doctor Who was not classed as science fiction.
While it was "possible to imagine" some of the concepts in Star Trek being real, he said of the Doctor's gadgets: "But the sonic screwdriver? I don't think so. Doctor Who's science is pixel thin."
He also found amusement in the way the Doctor had taken on a saintly glow since his television resurrection.
He had become "an amalgam" of Mother Teresa, Jesus Christ and Tinkerbell, he said.
"There is nothing he doesn’t know, and nothing he can’t do. He is now becoming God, given that the position is vacant."
Pratchett mused: "Perhaps they should start transmitting the programme on Sundays."
However, he said he would continue watching Doctor Who because it was "very very entertaining, with its heart in the right place, even if its head is often in orbit around Jupiter".