If the late environmental rights activist and leader of the Movement for the Survival of Ogoni People, MOSOP, Ken Saro-Wiwa was alive, he would have been 74 years old on October 10.

Moreso, by Tuesday, November 10, it will be exactly 20 years since Saro-Wiwa was executed with eight other Ogoni leaders by the military government of late General Sani Abacha.

But barely five days to commemorate the 20th anniversary of their execution, a sculpture created as a memorial and sent to Nigeria as a gift, reportedly being impounded by Customs officials in Lagos, was yet to be released, reports the UK Guardian.

The Bus memorial to Ken Saro-Wiwa and the Ogoni eight, made by artist Sokari Douglas Camp in 2006. Photograph: Martin LeSanto-Smith

The Sokari Douglas Camp’s sculpture, in the form of a steel bus, was said to have been impounded by the Customs authority, when it arrived at the Lagos port on September 8, purportedly on grounds of its “political value.”

Leaflets and reports sent by courier to commemorate Saro-Wiwa’s life and death were also allegedly seized.

Subsequent efforts by the Movement for the Survival of the Ogoni People, Social Action and other pressure groups have failed to secure the work’s release and a memorial vigil in Bori-Ogoni may have to go ahead without it.

Celestine AkpoBari, national coordinator for the Ogoni Solidarity Forum-Nigeria, has spent the past two months working to secure the release of the sculpture, called The Bus – Living Memorial, from a secure area of Lagos port and remains determined to get it to Ogoniland, nine hours’ drive from Lagos, next week.

“I have been fortunate to see the bus in London but it will be so exciting to see it in Nigeria, I don’t know if I might faint,” he told the Guardian. “It will give so much happiness and strength and every Ogoni will want to come home and see it. We are still looking forward to hearing the good news, we need the bus because it is the symbol of our struggle now that Ken is not with us. We will use the presence of the bus to begin another era of our campaign for justice.”

The Bus was commissioned following a competition to mark the 10th anniversary of the executions and first exhibited outside the Guardian’s London offices in 2006. The artist described her work as a “spectacle” and symbol of the importance of transport to environmental debate.

The Bus memorial to Ken Saro-Wiwa and the Ogoni 8 means to the Ogoni struggle for environmental justice in the Niger Delta. The Bus was made by Sokari Douglas Camp in 2006 and was the result of an international competition to create the Living Memorial to Ken Saro-Wiwa, initiated by Platform.

It was given to the Ogoni people by UK campaign group Platform, to show solidarity with continuing efforts to get oil giant Shell to repair damage caused by spills in Ogoniland over many years.

Saro-Wiwa’s hanging on 10 November 1995 sparked international outrage and led to the country’s suspension from the Commonwealth for four years, until the military handed control back to a civilian government in 1999.

In 2009, Shell agreed to pay $15.5m (£9.6m) to settle a claim brought by relatives of the Ogoni nine, after it was accused of having collaborated in the violation of their human rights.

The Bus spent four days at the bottom of the Thames in August, after it was dropped while being loaded on to a ship at the Port of Tilbury in Kent, and was repaired before leaving the UK for Lagos on 19 August. The plan was for it to make several stops in Nigeria en route to its final destination in Ogoniland.