Rt Hon Keith Vaz, chair of the Home Affairs Select Committee, has called for a "clear code of conduct" for police officers operating undercover.
He told ITV News that cases of undercover police officers fathering children with their subjects, or using the identities of children who have died, were "abhorrent".
"This isn't James Bond, this is happening," he added.
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Sergeant Elor Azaria was caught on video shooting dead the wounded assailant, sparking one of the most divisive cases in Israel's history.
CAFOD said: "Hunger is evident in the thinness of children, and the way clothes hang from the bodies of people already suffering."
Police believe it is a "distinct possibility" that Halliwell was a serial killer, beyond the two murders he was convicted for.