This could now overlap with BAAs application for a second runway at the airport.
Kelly asked for more information about the capacity increase last week especially regarding night time noise restrictions.
This means that a final decision cannot be made until September at the earliest, 11 months after the planning inquiry ended.
"It relates to a matter which could have been dealt with six months ago," said Stop Stansted Expansion (SSE) Campaign Director, Carol Barbone.
"One could simply put this down to dithering and inefficiency but we suspect that the Government is deliberately trying to buy more time."
BAA also applied for planning permission to build a second runway at Stansted in March this year. Kelly ordered a public inquiry into this on Monday, and this is expected to take place next
Stansted local authority Uttlesford District Council (UDC) questioned how the government can deal with the application for the new runway when it still hasn’t managed to make a decision
on the application to increase passenger numbers.
UDC has already postponed the closing date for objections to the second runway application from June to September, following earlier government delays and it says a further postponement may
now be needed. BAA said it was confident its applications would succeed.
"We now confidently look forward to presenting our case in front of an independent inspector at the forthcoming planning inquiry," said BAA Stansted Generation 2 (G2) project director