(CNN) A presidential runoff election in Haiti was postponed Friday amid what electoral authorities called threats and "security concerns."
The election -- marred by opposition calls for a boycott, sometimes violent protests and allegations of fraud during a first round -- had already been postponed once, from December 27 to Sunday.
The president of the Provisional Electoral Council (CEP), Pierre-Louis Opont, said in a statement Friday that the vote to elect a successor to President Michel Martelly was being pushed back because of arson and attempts to set public buildings on fire.
The postponement was made "in an effort to protect the life of voters, of the CEP personnel, the institution itself, particularly school buildings placed at the disposal of the CEP," the statement said.
The council, which oversees the election, did not set a new date for the vote.
In October, ruling party candidate Jovenel Moise defeated opposition candidate Jude Celestin in a field of 54 candidates in balloting that opponents of Martelly said was marred by fraud.
Celestin said via Twitter this week that he would boycott Sunday's vote.
A Friday afternoon press conference in which Martelly was expected to address the situation was abruptly canceled.
Martelly, a bad-boy musician known as "Sweet Micky," defeated former Haitian first lady Mirlande Manigat in an April 2011 presidential runoff. He was sworn in as president of the troubled Caribbean nation the following month.
The last presidential vote was also tainted by charges of vote-rigging and other irregularities.
Martelly is supposed to leave office on February 7.