Ben van Beurden says he is determined to make progress after further criticism over the spills in Ogoniland

Ben van Beurden, the chief executive of Shell, will go to Nigeria this week to try to restore his firm's tarnished reputation by winning local support for a clean-up strategy to tackle old oil spills in the Delta.

The Dutchman, who took over at the company at the start of this year, said he was determined to make progress where his predecessors had failed, after a damning report on pollution by the UN environment programme (Unep) nearly three years ago.

At its AGM in The Hague late last month, Shell was again criticised over the spills in Ogoniland, and was forced to admit that little progress had been made.

But Van Beurden hopes to make progress with the Nigerian government so that hundreds of millions of pounds, set aside by Shell after the Unep report but never spent, can be put to work.

"The commitment [to pay for clean-up] has always been there and I am sure [Van Beurden] will be discussing this issue with a variety of people when he is there. If that serves as progress it can only be a good thing," said a Shell spokesman.

The Unep report called for $1bn to be provided by Shell and others to pay for the restoration work needed after a range of spills, which Shell blamed largely on attacks on installations and pipelines.

Nigerian government data suggests there were more than 7,000 spills between 1970 and 2000 alone, including 2,000 official large spillages sites, many stretching back over decades.

Critics contrasted the effort made by BP to clean up after the Deepwater Horizon accident in the US Gulf with the lack of action by Shell and others in the Niger Delta.

The Anglo-Dutch oil group confirmed that "significant sums" were available for a restoration project that had been set up by the Nigerian government.

Celestine Akpobari, executive director of Social Action, a campaign group in Port Harcourt, said it would take about $100bn over 30 years to properly clean up an area where more than a million people live, but where many had lost their livelihoods from fishing and other activities as a result of the oil spills.

"I would like to meet [Van Beurden] but not in any executive office but in the field, I would like him to see for himself how the Ogoni people are now living in poverty," he said.

Akpobari said Shell had tried to help by paying those affected by spills to work on restoration, but this had only made matters worse. "Our communities are split in half between those who are paid and support Shell and those who are not. Every community where Shell operates there is a crisis of one kind or another."

Shell denies this but admits it tries to create local employment by hiring villagers to help with cleanups, which continue daily in a variety of places. The company says it has implemented 22 recommendations made specifically for Shell Nigeria by Unep.

But Sarah Shoraka of the London-based campaign group Platform, said Shell's claims that it needed to wait for the Nigerian government to act were ridiculous because everyone knew that the oil group was "in the driving seat".

She said: "The petroleum minister was a former director of Shell Nigeria for 15 years. Van Beurden says he is travelling to Nigeria in the next two weeks. He needs to get his head together with the Nigerian government to set up an Ogoni restoration authority and fund if he is serious about delivering the cleanup."