The German manufacturer has been in talks with the seven-time champion for weeks now as they look to extend their partnership beyond the end of this season.
Recently, both Mercedes and Hamilton expressed some optimism that a deal could get across the line imminently with several meetings to discuss the matter having been arranged.
However, still nothing has been signed and Mercedes boss Toto Wolff said at the Austrian Grand Prix that there would be no further developments before the British Grand Prix.
The delays have fuelled speculation that there could be key roadblocks in the deal, and even that there is the possibility of talks collapsing and both parties going their separate ways.
But Wolff has played down such suggestions and says that the contract is only taking so long because there is a desire to tidy up some final details.
“We want to do it super, to every detail, and sometimes you can have a situation where everything is carved out,” he explained.
“But this is not a money discussion at all. It is about the future, it is: what is it that we want to do right and optimise.
Source: Autosport