Cities around the world are commemorating the 11th anniversary of the execution of Nigerian writer Ken Saro-Wiwa and eight other activists.

A portrait of late human right activist Ken Saro-Wiwa

Analysts say the growing armed resistance in oil-rich Niger Delta mirrors the struggle of popular writer Ken Saro-Wiwa.

Saro-Wiwa led a robust, non-violent protest against environmental damage to his native Ogoni and the Niger Delta. His campaign focused on government policies in the region which he claimed had been polluted by Shell, Chevron and other western oil companies.

In 1994, Saro-Wiwa was arrested and was charged with "incitement to murder.  He and eight associates were executed 18 months later following a trial that did not meet standards established by international law

Since then, agitation in the Niger Delta has become more violent with kidnappings and attacks on the oil industry.

Ledum Mitee, a Nigerian lawyer and activist who was charged along with the others but later acquitted, says the execution of Saro-Wiwa marked a more deadly phase of the Niger Delta struggle.

"If you listen to most of the militants, if you accost them. When I go and challenge them to say, why do you take up arms, they say Ken tried it, non-violently and he was killed in such a manner," he noted.  "And so what happened to Ken has become an excuse for the violence. The challenge is to show that the non-violent method can attract sufficient attention and positive reaction from the government than the violent option. Unfortunately, what we see today is a reinforcement of that perception; that it is when you carry guns, when you take people hostage, when you sabotage facilities; that is when government will try to do something."

Saro-Wiwa's relentless campaign against oil companies in Nigeria drew global attention.

In the Niger Delta, Mitee says Saro-Wiwa remains an icon for social justice and would be remembered on this anniversary with special events.

"Here in Port Harcourt we are doing some rallies," he added.  "We are also doing something in Bori, in Ogoni, rallies in Ogoni villages, doing night vigil. In other parts, there is also some event in London and other parts of the world. In Washington, DC, Ogonis and their friends are also planning to do a walkout."

A recent report by a panel of independent experts say about 1.5 million tons of oil has been spilled in the Niger Delta in the past 50 years.

The report characterized the region as one of five most polluted spots on the planet.