On Tuesday, the source said that contact had been established with the pirates and that they were ready to communicate on a daily basis.
"There was [a new contact]. We talked to the captain. There are no changes," the source said, adding that no demands had been put forward so far.
According to the source, a doctor is expected to visit the sailors and provide them with necessary medicines.
Earlier in the day, the Russian Embassy in Cameroon said that the talks about freeing Russian sailors for ransom might last up to two weeks.
The Marmalaita, a multipurpose cargo vessel belonging to German company MarConsult Schiffahrt and sailing under the flag of Antigua and Barbuda, was attacked by pirates near Cameroon's Douala port on August 15. The pirates abducted eight out of the 12 crew members. The vessel itself was not seized and is still anchored in the port.