Sands said the figure is expected to rise, according to the Bahamas Press.
Seventeen of the fatalities were in the Abaco Islands where Dorian hit on Sunday and three were in Grand Bahama where it hit on Monday, he added.
Three of the 20 died in a hospital in New Providence where the Bahamian capital, Nassau, is located, the Efe news reported.
Prime Minister Hubert Minnis is scheduled to address the nation at 8 p.m. local time.
Meanwhile, the White House reported on Wednesday that US President Donald Trump called Minnis to offer his condolences for the deaths and damage caused by Dorian and pledged assistance to help the affected areas to recover.
In addition, Canadian Prime Minister Justin Trudeau said that he had also spoken with Minnis and announced that he would grant economic aid to the Atlantic archipelago.
Rescue teams are continuing their work in the affected regions.
Bahamian National Security Minister Marvin Dames said that there are more than 600 police and Marines on Grand Bahama Island and nearly 100 in the Abaco Islands to assist with the rescue operation, according to local media.
The US Coast Guard and NGOs are working on the ground to bring food and medicine to survivors.
( With inputs from IANS )