Residents would be blocked from challenging developments within 500 metres of transit stations under sweeping reforms to the Ontario Municipal Board to be unveiled next week.

The provision, revealed to The Globe and Mail by government sources, would allow municipalities to bar challenges to approved developments near GO Transit, subway or light-rail stations in order to support the goal of boosting density near transit lines.

But it is expected to alarm some neighbourhood associations, particularly in Toronto, where developers are eager to build increasingly tall condominium towers – and where residents have resisted such efforts near transit.

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The provision is part of a package of proposed legislative changes designed to dramatically scale back the powers of the OMB – long criticized as too developer-friendly – and hand more power over land-use decisions to municipal councils.

One official who is familiar with the proposals but not authorized to speak to the media said the system would allow municipalities to exceed the province's minimum standards for higher-density development near transit stations if they choose – without having to face local residents who oppose the plans at an OMB appeal.

Geoff Kettel, co-chairman of the Federation of North Toronto Residents' Associations (FoNTRA), said the provision could make it even harder to protect the character of established neighbourhoods, citing the higher-density zoning now being allowed along Eglinton Avenue near low-density Leaside to accompany the Eglinton Crosstown light-rail line.

He said he supports higher density close to transit stations in general, but argued that a 500-metre protected zone would go too far. "It's a sledgehammer, when you didn't need to be that brusque about it," Mr. Kettel said.

But he does support many of the reforms under consideration that would weaken the OMB, where he says citizen fights are costly and weighted unfairly toward developers.

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The balance of the OMB changes are expected to encounter opposition from developers, who warn they could embolden NIMBY activists and make developments harder to build, even as the Greater Toronto Area faces a housing squeeze. A delegation of developers met with Premier Kathleen Wynne last month to press their case.

Still, Joe Vaccaro, the chief executive officer of the Ontario Home Builders' Association, said developers would welcome the "new certainty" that would come with a provision to protect development near transit stations, where the province has said it wants to increase density.

"I would imagine that ratepayer groups would be up in arms," Mr. Vaccaro said. "It is almost like trying to find a way to shield the municipalities … by saying to them: 'If you make that tough decision, you don't have to worry about the OMB appeal. We're going to shield you from your angry residents.'"

The reform package comes after a lengthy review process, years of criticism of the OMB and recent headlines about a 35-storey condo on a site next to a Toronto public school in Ms. Wynne's own midtown riding.

Other changes expected to be included were drawn from wish lists of the OMB's critics. They include restricting the OMB to reviewing decisions by municipal councils rather than starting its own hearings from scratch; using written submissions rather than time-consuming oral hearings; moving to a panel instead of having one member pass judgment on major development projects; strictly limiting the OMB's authority to rule on whether a development adheres to a municipality's official plan; and barring challenges of municipal official plans.

With files from Adrian Morrow and Justin Giovannetti