MANILA (Reuters) - A former police general who oversaw the bloodiest years of the Philippines’ war on drugs shrugged off the killing by police of a 3-year-old girl in a sting operation, saying on Thursday the world was not perfect and “shit happens”.

Ronald dela Rosa, a senator who once led the crackdown that has killed thousands of mostly urban poor users and peddlers, said “collateral damage” was inevitable, referring to Sunday’s killing of toddler Myka Ulpina in a province near Manila.

Police said she was used as a human shield by her father, a suspected drug dealer who resisted arrest and opened fire. The girl’s mother has rejected that version of events.

“We are living in an imperfect world,” dela Rosa told a news conference.

“Would a police officer want to shoot a child? Never, because they have children as well. But shit happens during operations,” he said.

Separately, more than two dozen countries formally called on Thursday for a United Nations investigation into President Rodrigo Duterte’s crackdown, according to activists.

Their draft resolution marks the first time that the Human Rights Council is being asked to address what 11 U.N. rights experts said last month was “a staggering number of unlawful deaths and police killings”, which the government had shown no interest in investigating. Duterte’s spokesman had called that “outrageous interference” by “foreign propagandists”.

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Duterte’s critics say his three-year-old campaign has been a failure, intended to create shock and fear and burnish his tough image without making a dent on big narcotics syndicates.

Allegations of police cover-ups, summary executions and planting of drugs and guns are widespread.

Police reject the allegations and say all of the more than 6,000 people they say they have killed were all armed and had all resisted arrest during official, sanctioned operations.

Activists say the drug-related killings could be closer to 27,000.

Police spokesman Bernard Banac said officers involved in the child’s killing were suspended pending an impartial investigation to determine which firearm killed her.

He reiterated the police version that the girl’s father pulled a gun first.

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“It cannot be helped if there was an accident ... if he used his daughter as a human shield,” he said.

Lawyers and activists slammed dela Rosa and said a day of reckoning would come for police who killed illegally.

“This is not ‘shit happens’. This happens when gov’t dispenses justice from guns instead of courts,” Jose Manuel Diokno, a lawyer who has mounted legal challenges to Duterte’s crackdown, said on Twitter.

Carlos Conde, Philippines researcher for the New York-based Human Rights Watch, said dela Rosa had shown “an uncaring, even contemptuous attitude” towards the child’s killing.

“Dela Rosa should be reminded that he, too, will answer for his complicity in the slaughter of thousands,” Conde said.