Nine used syringe needles were found buried and 'pointing up' in sand at a children's play area.
Council bosses believe the positioning of the needles suggested they were 'buried in the sand deliberately'.
There have been no reported injuries.
The alarm was raised after the needles were spotted and reported by a resident, shocked council chiefs revealed.
The horrific discovery was made at Norley Hall Adventure Playground on Lamberhead Road near Pemberton in Wigan.
Wigan council said the play area was also damaged in a suspected arson attack last weekend and remains closed to children as a result.
They described the needles as an 'isolated incident' but the playground is being monitored.
It's not known whether police have been informed.
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The council however is now urging residents and children to remain vigilant after needles were discovered.
A council spokesman said: "Nine syringes have been removed from the sand area at Norley Hall playground after a report from a local resident.
"The needles were pointing up as if buried in the sand deliberately."
Kathryn Rees, assistant director for transformation at the council, said there were a number of needle exchanges across the borough where needles could be disposed of safely.
She said: "We are absolutely appalled that somebody would deliberately do this at a children's play area.
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"We will not tolerate anti-social behaviour which poses a real threat to our communities and would urge any residents with concerns to speak to us.
"Although we believe it is an isolated incident in this area we would encourage people to be vigilant when visiting their local park and please report anything suspicious to the police.”
"The council is monitoring the play area at Norley Hall."
The council urged anyone who finds a needle in a public area to report it to the council.
Needles should never be picked up or touched.
The council spokesman added: "If you are concerned about a potential needle injury you should seek medical advice immediately."
