Repeating his call for the release of democracy icon Aung San Suu Kyi, Secretary General Ban Ki-moon described Myanmar's "lack of engagement" in providing free and fair elections as "frustrating".
The first election to be held in Myanmar in nearly two decades has already been slammed by the international community as a sham.
"Myanmar's lack of engagement is deeply frustrating, as it not only contradicts its stated policy of cooperation with the United Nations but also limits my ability to fully implement the mandate entrusted to me by the General Assembly," Ban said, in his latest report on the country.
The Union Election Commission in Myanmar has already dissolved ten political parties prior to the general elections.
The dissolved parties included Suu Kyi's National League for Democracy (NLD), which, along with four others, was struck down for failing to renew their registration.
In March, after the election laws were issued, Ban said that the "published electoral laws" and the "overall electoral environment" did not "measure up to what is needed for an inclusive political process".
A new election law bars any person convicted of a crime from being a member of a political party.
Since pro-democracy icon, Suu Kyi was found guilty of breaching the terms of her already existing house arrest in August, this law effectively ends the chances of her running.
Acknowledging that over 130 political prisoners had been released, Ban underlined that other political prisoners including Suu Kyi needed to be released.
"I strongly urge the Myanmar authorities, once again, to release, without delay, all the remaining political prisoners, including Daw Aung San Suu Kyi, so that they can freely participate in the political life of their country," Ban wrote.
"This will be the clearest signal of their commitment to a credible electoral process," he added.
Aung San Suu Kyi has spent most of the past two decades under house arrest. Her NLD won the last election in 1990 but she was never allowed to take power. The junta has banned the NLD from taking part in this vote.