Gabon disbanded the main opposition party on Wednesday after one of its leaders declared himself president, claiming inspiration from power struggles in Tunisia and Ivory Coast.
The row marks a step up in tensions in the usually sleepy central African country since Ali Bongo Odimba took over from his father Omar in 2009 after a disputed vote, and shows the scope for political protest to cross borders in Africa.
Let us assume our responsibilities, Andre Mba Obame, who has always contested his defeat in a August 2009 poll, told thousands of supporters at a swearing-in ceremony staged at the headquarters of the National Union (UN) party in Libreville.
We are no less brave than the Ivorians... We are no less brave than the Tunisians. History is on the march, let's go!, declared the former minister, naming key posts in what he called Gabon's legitimate government.
Ivory Coast incumbent Laurent Gbagbo has refused to step down despite U.N.-certified results showing a November 28 poll was won by Alassane Ouattara. Outtara has declared himself president and runs a parallel government out of a U.N.-guarded hotel.
An uprising in Tunisia this month led to the toppling of former leader Zine al-Abidine Ben Ali, and demonstrators want a purge of former regime loyalists in an interim government.
Bongo's election on 2009 led to days of rioting across the country as opponents accused him of vote-rigging. Final results put Bongo first with 41.79 percent, veteran opposition figure Pierre Mamboundou second with 25.66 percent and Mba Obame third with 25.33 percent.
In stark contrast to Ivory Coast's Gbagbo, who now has pariah status abroad, Bongo has wide international recognition as oil-rich Gabon's leader, including from former colonial power France which cemented ties with a defence deal last year.
The Interior Ministry said the National Union, which was formed from the merger of three defeated opposition parties after the August poll, had been dissolved with immediate effect.
This constitutes a crime of high treason punishable by law, said Interior Minister Jean-Francois Ndongou, not specifying whether Mba Obame would face legal action.
Gabon, one of the few sub-Saharan countries with a Eurobond , is battling to diversify its economy as its oil runs out.
Investors have broadly welcomed Bongo's attempts to boost sectors such as the local timber processing industry, tourism and mining, and welcome his attempts to trim a huge civil service bloated by patronage under his father.
However, the reform process has been slow, and few expect major progress before a legislative election due late this year where Bongo is seen needing to emerge with a majority in parliament to be able to pursue the drive at all.