FUTURE developments in Newham could be hit with a “Crossrail tax”, under new plans unveiled by mayor Boris Johnson.

The so-called community infrastructure levy would contribute around �300 million to the total �17 billion cost of the rail link.

Developers in Newham would be charged �20 per square metre on projects which win planning approval from Spring 2012, although medical and educational buildings would be exempt.

The charge will vary across London. In boroughs such as Camden and Islington it will be �50 per square metre, while in others such as Hackney and Tower Hamlets the figure is �35.

The move could see a drop in the cash provided by Section 106 — or “planning gain” — agreements, potentially meaning less money for council bosses to allocate to other community improvements.

They will be obliged to take account of the new charges when negotiating such agreements.

The mayor is currently consulting on the plans and any responses must be received by March 1.

Mr Johnson said: “There is no underestimating how important Crossrail is to the future of this great city.

“Every corner of London will benefit once construction is complete and despite the current financial pressures, I am committed to ensuring London meets its fair share of the cost.

“It is right that the sector that will benefit so much should make its contribution and I am confident that this will not hinder development in the capital.”

The Crossrail line will run east to west, from Maidenhead through a tunnel under central London, with branches to Shenfield and Abbey Wood, and a spur to Heathrow airport.

Services will call at five stations in Newham - including Custom House, which will be completely rebuilt - and it is estimated the borough’s economy will be boosted by up to �100m.

Some businesses are already paying an extra two per cent on top of their business rates to help finance the project.