* IndiGo says planes grounded because no spare engines
* Says has led to some flight cancellations
* IndiGo has faced Airbus delivery delays due to engine issues (Adds updated IndiGo statement)
NEW DELHI, Aug 18 (Reuters) - India's biggest airline IndiGo said on Friday it had been forced to ground 12 Airbus jets because of delays in getting new Pratt and Whitney-made engines and uncertainty around a new Indian sales tax.
In a statement following local media reports of new grounded planes, the carrier said eight of its A320neo aircraft had been grounded since April.
Four A320ceo were also grounded last month because spare engines are stuck at customs, which the company linked to clarifications related to a new country-wide sales tax.
IndiGo, owned by InterGlobe Aviation, and rival GoAir have faced delays in receiving planes from Airbus due to ongoing problems with engines developed by Pratt and Whitney, owned by United Technologies.
Pratt & Whitney did not immediately respond to a request for comment.
Local media on Friday had reported that 13 planes had been grounded, and that the airline was forced to cancel 84 flights.
IndiGo, which has 95 aircraft in service, said it had previously flagged up the grounding of nine A320neos in June because of a lack of spare engines.
The shortages have "led to unplanned flight cancellations. All passengers have been informed of the changes and accommodated accordingly," the airline said.
IndiGo said in an earlier statement some sections of the media had spread misleading information on the cancellations.
"Our schedule has already been planned in the month of June on non-availability of these aircraft for the month of July, August and September. The affected passengers have already been accommodated with suitable options," it said.
IndiGo, which flies four in every 10 Indian air passengers, operates around 900 daily flights.
Shares in InterGlobe closed down 3.27 percent, against a 0.85 percent drop in the wider market. (Reporting by Tommy Wilkes; Editing by Jane Merriman and David Evans)