MPs supporting Boris Johnson’s controversial plans for a Silvertown tunnel under the Thames have been accused of being “ill-advised and irresponsible” by campaigners fighting the proposal.

Four east London MPs signed a letter along with two MPs the other side of the river pushing for more road crossings, including a tunnel linking Silvertown with the Greenwich Peninsula to bypass to the heavily-congested Blackwall Tunnel and the A12 through Poplar and Bromley-by-Bow.

But the No To Silvertown Tunnel campaign claims the MPs are ignoring evidence that a new tunnel will “push more traffic into streets around Canning Town, Plaistow, West Ham and Stratford” as well as increase levels through south east London.

“We want to see east London thrive—but a Silvertown Tunnel won’t deliver that,” claimed the campaign’s Darryl Chamberlain.

“It offers nothing but the aggravation of jams and the health consequences of high pollution. The MPs are ill-advised and irresponsible.”

Another crossing will increase traffic from Essex and Kent for drivers avoiding the Dartford tolls, rather than relieve Blackwall Tunnel traffic, say campaigners.

Instead, they argue, public transport links such as the Jubilee Line extension and the DLR have led to economic growth.

But the MPs’ letter points out that the Olympic Park, London City Airport, ExCel, the Royal Docks development and the O2 Arena means new bridges and tunnels are needed “to help cope with demand and continued regeneration.”

It was signed by Poplar & Limehouse MP Jim Fitzpatrick, Bethnal Green & Bow’s Rushanara Ali, East Ham’s Stephen Timms and Barking’s Margaret Hodge. Other MPs involved were Nick Raynsford at Greenwich & Woolwich and Teresa Pearce at Erith & Thamesmead.

“Congested tunnels at Blackwall where rush-hour commuters are delayed by an average 19 minutes and an archaic tunnel at Rotherhithe are clearly no longer sustainable,” the letter to Boris Johnson states.

“Your support for a new tunnel between Silvertown and Greenwich is welcome, but an additional link is not enough to cope with forecast population growth.”

Proposals for a ferry at Gallions Reach rather than a bridge or tunnel were dismissed as inadequate, after a public consultation showed a bridge would be more popular with six times more capacity, the MPs point out.

A proposed bridge at Gallions Reach envisaged when Ken Livingstone was Mayor was scrapped when Boris Johnson won control at City Hall in 2008. Further public consultations are due in the New Year.