European Union chief negotiator Michel Barnier told reporters that "work continues," as he arrived for the second day of talks, AFP wrote.
Both men warned that a deal could not be reached without major concessions from the other party.
There are only five weeks to go until the end of the current transition period, during which trade relations have remained largely unchanged.
The two key sticking points remain post-Brexit access to British fishing waters for European vessels and the EU's demand for trade penalties if either side diverges from common standards or state aid regulations rules.
Raab said that this could be the final week of "substantive" talks, with time running out to agree and ratify a deal.
"On fishing there's a point of principle: as we leave the EU we're going to be an independent... coastal state and we've got to be able to control our waters," he added.
Barnier told envoys last week that London was asking that European access to UK waters be cut by 80 percent, while the EU was willing to accept 15 to 18 percent.
A British official called the demands "risible", adding that the "EU side know full well that we would never accept this."
A failure to reach an agreement would see Britain and the EU trading on World Trade Organization terms, with tariffs immediately imposed on goods travelling to and from the continent.
As it stands, Britain will leave Europe's trade and customs area on December 31, with no prospect of an extension.
A no-deal scenario is widely expected to cause economic chaos, with customs checks required at borders.