A temporary slipway has opened in Putney to maintain access to the river while the Thames Tideway Tunnel is built.

The announcement comes ahead of works to construct the 25km tunnel that will run under the river bed from west to east London.

Thames Tideway Tunnel is a major expansion of London's sewage network which aims to protect the Thames from pollution, and the scheme hopes to stop millions of tonnes of wastewater spreading into the river.

Ben Green, Tideway delivery manager, said: "The temporary slipway is an important milestone for us, as it allows for us to prepare the site for the main work that needs to be done to connect the tunnel to one of the most polluting discharge points under Putney Bridge.

"It's simply wrong that in this day and age, an average 68,000 tonnes of sewage pours out of our two gates under the bridge, polluting the river just yards upstream from one of the busiest stretches of water for rowing in Britain.

Justine Greening, MP for Putney, cut the ribbon to mark the official opening on Tuesday last week.

She said: "Access to the river is a vital part of the community in Putney and I am really pleased to see the new slipway open during the summer, when the river becomes an extended playground for the area.

"The Thames Tideway Tunnel is an essential infrastructure project for London, and will have a hugely positive impact on the river's health and quality.

"As it enters its main construction phase, it's very welcome that Tideway is engaging with the local community and keeping disruption to a minimum whilst this vital work takes place."

The main works at Putney Embankment began at the end of July and, once complete, sewage overflowing into the river under Putney Bridge will be captured down a 36m deep shaft in the foreshore.

From there, a 48m long connection tunnel will take sewage to the main tunnel and transfer it to east London for treatment.

Construction of the tunnel is being completed in three parts, east, west and central London, and is expected to be completed by 2024.