PORT HARCOURT, Nigeria (Reuters) - Nigerian security forces fired tear gas on Wednesday to prevent hundreds of youths loyal to President Goodluck Jonathan and to his bitter rival, Rivers state governor Rotimi Amaechi, clashing in the main oil hub of Port Harcourt.
A Reuters witness saw around 2,000 youths from the two factions arrive in some 30 commercial buses at the Rivers state parliament in Port Harcourt, the main hub of Africa's biggest energy industry in the swampy Niger Delta and historically a flashpoint for political violence.
Police struggled to keep them apart until a Joint Task Force composed of both military and police stepped in, firing tear gas canisters and chasing away the crowds. One man was arrested.
Last month, police banned demonstrations in the hub of Nigeria's two million barrel a day industry to prevent clashes.
"The ban on rallies and protests is still on. Anyone caught holding protests will be dealt with," Rivers state police spokeswoman Angela Agabe said.
Amaechi and Jonathan have been embroiled in a spat in the past few months which worsened when Amaechi was elected head of the National Governors' Forum grouping Nigeria's 36 states.
Jonathan, also from the oil-producing Niger Delta, and his backers have refused to recognize Amaechi because of his open opposition to the president seeking another term in an election scheduled for 2015. Jonathan has not officially declared he will run but his supporters say he will.
Many of Nigeria's governors, and quite a few lawmakers, are in revolt against Jonathan over his expected plan to run, including many within his own People's Democratic Party (PDP).
Security officials and oil workers fear Port Harcourt -- once a fiefdom of militants, gangsters and kidnappers targeting the oil industry - will become a key battleground in this power struggle, as it has in the past.
Representatives of Jonathan and Amaechi were not immediately available for comment on Wednesday.
Violence between specially bused-in youths, sometimes armed, has been a feature of Nigerian electoral cycles since its return to democracy in 1999, but the spat over Jonathan's future plans risks triggering violence way ahead of time, analysts say.
(Reporting by Jackson Ohameje; Writing by Tim Cocks, Editing by Gareth Jones)