By Rajeev Khanna BBC reporter in Ahmedabad

A recently-concluded kite festival in India has left hundreds of birds with nasty injuries.

The thread used to fly kites is laced with glass shards - a tactic to bring down competitors' kites, but which ends up entangling birds mid-flight causing multiple injuries.

Although this happens every year, the number of those injured is believed to have increased this time with kites being flown well beyond the festival days.

Unfortunately 90% of these birds are never able to fly again Voluntary animal carer Rahul Sehgal

The co-ordinator of a voluntary group for animal care in the western city of Ahmedabad, Rahul Sehgal, says his centre has received more than 150 injured birds since December and they expect bird casualties to continue until next month.

No escape for cows

Of these, 100 are - ironically enough - kites, while others include vultures, pigeons and owls.

Owls are among the victims of kites

Mr Sehgal said most birds damage their shoulder muscles after getting entangled in the kite thread and are then unable to flap their wings.

''Unfortunately 90% of these birds are never able to fly again," he said.

He also said the potentially fatal glass-laced thread posed similar dangers to animals.

Cows too are believed to have died due to the kite threads.

Unknown toll

The phenomenon is common across the state - but Ahmedabad is one of a few places with centres that treat injured animals.

In most other places, particularly rural areas, such incidents are hardly ever reported.

Mr Sehgal said: "It's not possible to ask people to stop flying kites - especially at a festival that marks the sport.

"But what can be done is some serious thinking about using other thread that will not injure the birds so badly."