LONDON, Nov 1 (Reuters) - Russia does not need a presidential decree to formalise the completion of the partial mobilisation of reservists to fight in Ukraine, a senior senator from Russia's ruling party said on Tuesday.

Russia has announced the completion of a mobilisation ordered by President Vladimir Putin, declaring it had called up 300,000 reservists in a little more than a month, and no more are needed.

But the suggestion that Putin might not issue a formal decree calling an end to the drive may increase concern among Russians that the mobilisations could still be restarted.

When asked on Monday if he would issue a decree to formalise the completion of the mobilisation, Putin said he had not considered whether or not one was needed and would consult with lawyers.

"No additional decrees on the end of mobilisation are required," Andrei Klishas, head of the committee on constitutional legislation in the Federation Council upper house was quoted as saying by TASS news agency on Tuesday.

Putin declared the "partial mobilisation" of 300,000 reservists on Sept. 21, after a series of military defeats. The mobilisation touched off an exodus of military age men from Russia, with tens of thousands heading for countries including Georgia, Armenia and Kazakhstan.

Defence Secretary Sergei Shoigu said 300,000 Russian reservists had been mobilised, with 82,000 already deployed to the conflict zone. (Reporting by Guy Faulconbridge Editing by Peter Graff)