Long-ruling President Ilham Aliyev has brought the date of Azerbaijan's presidential election forward by more than six months, to April 11, in a move that swiftly drew sharp criticism from his beleaguered opponents.

The new date for the vote, which had been scheduled for October 17, was set in a decree announced on the president's website on February 5.

The decree did not explain the reasons for the decision, which it said was made in accordance with the constitution and the Electoral Code.

However, presidential adviser Ali Hasanov told state news agency Azartac that the election was being moved to ensure it didn't interfere with "important domestic and international events" later in the year.

Such events include centenary celebrations of the Azerbaijan People's Republic, an independent state that existed for nearly two years after the collapse of the Russian Empire.

However, the leader of the opposition Musavat Party, Arif Hacili denounced the change as "an operation to prolong Aliyev's rule for another seven years."

Speaking to RFE/RL, Hacili said he believed Aliyev's main goal is to prevent the opposition from properly preparing for the poll, but that he suspects internal disputes within the ruling elite played a part.

Citing what he said were "ongoing disagreements inside the government," he said that "they want to have the elections as soon as possible."

Another explanation for the change was that the state of Azerbaijan's economy has worried Aliyev.

"For the first time in the entire period of Ilham Aliyev's rule, elections are held in an economic and, indeed, systemic crisis in general, which creates certain risks for the government," the Turan news agency said in an analysis.

On February 1, Deputy Prime Minister Ali Ahmadov said Aliyev would be the candidate of the ruling New Azerbaijan Party (YAP) for the presidency again, potentially extending his rule to 2025.

Aliyev took office in the oil-producing Caspian Sea state in 2003 after his ailing father, Heydar Aliyev, tapped him as his favored successor.

The elder Aliyev, a former KGB officer and Soviet-era leader who had ruled independent Azerbaijan since 1993, died weeks after his son was sworn in.

Controversial Referendum

Ilham Aliyev has been accused by opponents, right groups and Western governments of persecuting activists, journalists, and opposition politicians, and of prolonging his time in office through undemocratic votes. He has repeatedly shrugged off the allegations and claims they are false, despite the evidence.

Now 56, Aliyev secured the right to decree early elections after the Constitution was amended in a controversial referendum in September 2016.

The referendum, condemned by the opposition and human rights activists as a tool to strengthen Aliyev's grip on power, also extended the presidential term from five to seven years.

It abolished the minimum age for presidential candidates, which used to be 35, sparking speculation that Aliyev was grooming his son, Heydar, who was 19 years old at the time, to eventually become president.

In February 2017, Aliyev appointed his wife, Mehriban Aliyeva, as first vice president -- a post also created by the referendum -- placing her first in line to take over if the president dies or is incapacitated.

In December, Azerbaijan's Electoral Code was also amended to allow snap presidential elections provided they are announced at least 60 days in advance.

With reporting by Bloomberg and Eurasianet