An underwater robot deployed on Tuesday to inspect the wreck located it at a depth of 2,700 metres (8,850 feet), some 15 miles (24 kilometres) off the southern coast of Gran Canaria island, she told reporters.
"It is a greater depth than we had expected," Pastor, who was speaking in Gran Canaria, added.
The Oleg Neydenov was carrying nearly 1,500 tonnes of fuel oil when it sank near the Canary Islands on April 15.
Bad weather since has prevented the authorities from plugging the leak and removing fuel that seeped out of the trawler.
Environmentalist group Greenpeace said the oil slick from the trawler extended for over 100 kilometres.
The group has criticised Spanish authorities for towing the trawler out to sea as a precaution after it caught fire on April 11 when the ship was moored at Las Palmas port on Gran Canaria, prompting the 72 crew to be evacuated.
The trawler sank four days later, about 15 miles (24 kilometres) south of Maspalomas, another town on Gran Canaria.
Environmentalists say the area where the ship sunk has deep-sea coral and a significant population of dolphins and turtles.
They recommend damaged ships be dealt with in ports or bays since oil spills can be harder to contain in the open sea.
The accident has stirred memories of Spain's worst environmental disaster when the Prestige oil tanker sank off the northwestern coast of Spain in 2002, sending 63,000 tonnes of fuel into the Atlantic Ocean.
While the Prestige was carrying over 50 times more oil than the Oleg Neydenov, Greenpeace has warned that the sinking of the Russian ship could still damage the environment.
Helicopter, boat patrol
A police helicopter and boat patrolled the area to search for any wildlife that may have been affected by the fuel, the public works ministry said in a statement.
So far they have rescued three Cory's shearwaters, a bird that lives on the ocean and only comes ashore to attend to its nests.
The birds were taken to an animal treatment centre on Gran Canaria, the public works ministry said in a statement.
The government has also sent a crew of 50 people from Tragsa, a state-owned firm specialising in mopping up oil spills, to Gran Canaria in case they are needed, the ministry added in a statement.
Another 150 Tragsa employees are on standby on other islands in the archipelago.
In January 2014, the Russian trawler was at the centre of a dispute between Russia and Senegal, which accused the Oleg Neydenov of fishing illegally in Senegalese waters.
Senegal seized the boat for three weeks and then towed it southwards towards the Guinea Bissau border.
The ship's owner, a group based in Murmansk in northwestern Russia, paid Dakar 900,000 euros ($950,000) to have it returned.