Parents of children attending St Michael's CE Primary, Grimsargh – who use the car park of St Michael's Church to cut congestion on Preston Road at the beginning and end of the school day – were informed of the potential danger by headteacher, Mrs Kathryn Ward on Monday.
Mrs Ward contacted parents via the school's text messaging system after police examined the scene, confirming the syringes were probably discarded by drug users.
She explained the school suspected there was a problem last week after someone reported seeing something under the ice while the car park was frozen.
On Monday a parent came to tell her that broken syringes and needles had been found at the back of the car park and after a more detailed search, it was discovered the problem was far worse than they first thought.
They found discarded syringes in the grass and at the back of the car park. The police and church were informed immediately and the area covered until officers arrived.
Some of the syringes had been squashed by vehicles using the site and although police removed what they could, Preston Council was called out to clean up the area, carrying out the work yesterday.
Mrs Ward described the situation as "a sad reflection of today's society" and said she would be telling children how important it was for them not to touch or pick such items up.
"We are worried about the safety of the children, parents and also parishioners," she added.
Although part of the car park was closed by police until the council cleared the area, it remained open for parents to use.
St Michael's vicar, the Rev Geoffrey Loxham said the church would now close the car park from 6.30pm to 7.30am each da from Monday.
He explained a two-barred gate was in place at the car park entrance, but they had only been using the top bar, to prevent larger vehicles using it.
They would now close the bottom bar, which had previously remained open to allow smaller vehicles entry.
"It is a shame people want to misuse a good community facility," said Mr Loxham, adding that the car park would still open at weekends and evenings when parish or church events were taking place.
He had no idea who had been using the car park for the suspected drug use.
Mr Loxham praised everyone concerned, saying: "Everyone responded as quickly as possible. The church, the school, the police and the council."
PCSO Gemma Duxbury, who said at least 15 syringes and needles had been found, said: "People need to be aware of what has been going on.
"It is dangerous, especially for the children at St Michael's.
"Police are going to be keeping an eye on the area and we have passed the information on to the response team. Hopefully the problem will stop."