Experts were on Saturday morning still unable to start probing the causes of a fire on board a German oil tanker in the Baltic Sea due to the risk of accumulated gases after the flames were extinguished. The ship must first be laid up to allow any dangerous gases to dissipate, a spokesman for the Rostock water police said. This degassing is important in order not to jeopardize the work of the fire investigators, he stressed. It remained to be seen when the investigation could begin. No new embers were found during the night, officials said. The ship is now docked and secured in Rostock harbour…