About 1,000 protesters have blocked waterways in Nigeria's Niger Delta to prevent Shell workers from reaching oil rigs, according to a youth leader.
Jonathan Omongu said the protest was a warning to the oil giant that the Nembe Island community wanted electricity, potable water and other basic amenities.
Some workers aboard three seized Shell boats are also being held, but would not be harmed, Mr Omongu said.
The southern oil-rich region is one of the most under-developed in Nigeria.
For several years bombings and kidnappings by militants in the Niger Delta - fighting for more rights and a share of oil wealth for local people - paralysed the oil industry.
Nearly three years ago, most militants accepted a government amnesty, but last month four policemen were killed by unidentified gunmen in the creeks around Nembe Island.
Shell has four flow stations and two oil rigs in Nembe Island - one of the largest communities in the oil-producing zones of Bayelsa state where about one million people live.
Alabo Nengi James, the chairman of Nembe town's oil and gas committee, said that the protest follows a meeting between the community and Shell that ended in deadlock on Monday.
He said despite the area's oil-wealth, the community has little to show for it and the residents want electricity, water and schools to be built by Shell.
According to the Reuters news agency, 14 members of Shell staff are being held by the protesters on the boats.
The Shell spokesman was unavailable for comment.