The long-awaited proposal to replace rundown buildings at Pincents Lane Retail Park with a warehouse from the Swedish retailer famous for its flat-pack furniture was given the green light by planning bosses at a tense four hour meeting last week.
But Reading West MP Alok Sharma, who was in the public gallery at Theale Green School, said: "While I, and many of my constituents, have always welcomed the jobs IKEA will bring, we have had serious concerns about potential traffic congestion on local roads.
"It was a split vote on the committee and I would much rather have preferred a unanimous decision, after a review of the traffic issues highlighted by local community representatives, and allowing local residents further comfort on the traffic mitigation measures outlined.
"I very much hope IKEA's assumptions on traffic flows are right, otherwise a planning decision made in haste will be repented at leisure by local residents stuck in traffic jams."
West Berkshire Council's eastern area planning commitee approved the £10m development, which will cover four hectares, with the store sitting to the north of Pincents Lane, opposite a 1,259-space car park and areas for buses and coaches. The two areas will be linked by an overhead walkway.
Furious residents heckled representatives from IKEA, who promised it was not in their interest to cause traffic chaos, and planning councillors argued the promise of 400 new jobs and £5m major road improvements was too good to turn down. But they instructed the planning officer to tear up the agreement if IKEA does not complete a legal agreement by August.
Roger Cooper, IKEA project manager, said: "We now have to take a step back and decide how we move forward with the discussions and legal agreement."