A dissident movement which spearheaded president Hosni Mubarak's overthrow in 2011 announced Wednesday a boycott of Egypt's presidential poll that it said would only serve to "enthrone" ex-army chief Abdel Fattah al-Sisi.
The April 6 movement was banned last month and its leader has been jailed, amid a crackdown by the military-installed regime on the opposition following the overthrow of Islamist president Mohamed Morsi in July.
The secular-leaning group had backed the army's ouster of Morsi, but then turned on the new regime as it clamped down on dissent.
Sisi, the army chief who toppled Morsi, is expected to stroll to victory in the May 26-27 election against his only rival, Hamdeen Sabbahi, a leftist politician.
April 6 "does not recognise the electoral process", the group's chief Amr Ali said in a press conference.
The elections "are only legal procedures to enthrone Abdel Fattah al-Sisi", Ali told AFP, urging April 6 supporters not to vote and to refuse to recognise the electoral process.
"The political life has been going from bad to worse during the past four months. This regime does not accept political pluralism", Ali said.
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Sisi, who retired from the army, has indicated he will have little patience for protests and unrest.
His supporters view him as a strong leader needed to restore stability in Egypt and kickstart its ailing economy.
At least 1,400 people, mostly Islamists, have been killed in street clashes since Morsi's overthrow and thousands have been imprisoned.
Almost 500 security personnel have also been killed in a wave of militant attacks.
Secular-leaning groups such as April 6 have increasingly protested against the government, accusing it of restricting freedom while giving police a free hand to crush dissent.
In December, April 6 founder Ahmed Maher was jailed for three years for violating a law banning all but police-sanctioned protests.