The spokesman for Russian President Vladimir Putin says it will take time to mend ties with Turkey after the November downing of a Russian military jet.

Recep Tayyip Erdogan sent a letter of formal apology to Putin on Monday, seven months after Turkey shot down the Russian jet on a mission in Syria, triggering a slew of Russian sanctions that have dealt a severe blow to the Turkish economy.

Putin's spokesman Dmitry Peskov on Tuesday called the apology "a very important" step but added that the ties between the two countries would not go back to where they were overnight.

Both Russia and Turkey will need to "take more than one step to meet each other," he said.