A faction of Yemen's separatist Southern Movement on Saturday called for a day of "civil disobedience" to disrupt next week's presidential election.
The Higher Council of the Peaceful Movement for the Liberation of the South, in a statement, called on its supporters to "take every possible peaceful action" against Tuesday's election to prevent it going ahead.
The group is one of several factions that make up a broader separatist coalition known as the Southern Movement that seek autonomy, and in some cases, independence, from the central government in Sanaa.
The Southern Movement opposes the election and has repeatedly called on its supporters to boycott the poll.
The Higher Council warned election day could turn violent and that their supporters would try to prevent voters from casting their ballots at polling stations in the former South Yemen.
"The Southern Movement will prevent the elections using peaceful means but we expect some violent actions may take place, especially in the big cities," the Higher Council's vice president, Saleh Yahia Said, told AFP.
Witnesses say posters have been plastered in the streets and on buildings in Yemen's southern port city of Aden calling for a boycott.
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"No to elections, yes to secession," said one poster. "Ensuring the failure of the elections is a national and religious duty," reads another.
A security official in Aden said police on Saturday foiled a planned attack on several polling stations in the city by "five members of a terror network," according to a statement released by the official SABA news agency.
The official, who spoke on condition of anonymity, did not identify the suspects but said they were arrested with "several explosive devices" in their possession.
Their aim is "to instil fear" among voters in an attempt to disrupt the presidential election, the official added.
On Friday, southern militants opposed to the election traded fire with police outside a polling station, leaving three civilians wounded, residents said.
Under a Gulf-sponsored accord signed in November, Vice President Abdrabuh Mansur Hadi will stand as the sole candidate to replace embattled President Ali Abdullah Saleh.
Saleh agreed to a power-transition deal after months of mass protests demanding his ouster.
The violence and political deadlock that engulfed Yemen since January 2011 has left hundreds dead and thousands more wounded. It has also crippled Yemen's already weak economy and pushed millions of Yemenis further into poverty.
Shiite rebels in northern Yemen have also called on their followers to boycott the election.