"We didn't take this decision in a hurry," the ministry's press service quotes the words of Foreign Minister Heiko Maas.
Earlier in the day, the Sueddeutsche Zeitung newspaper reported that the decision would be announced later Monday.
Similar actions were taken by France and other Western countries.
The report comes in wake of the same day's announcement of the summoning of Russian envoys to Lithuania's, Latvia, and Estonia to the Ministries of Foreign Affairs of the respective nations.
Reacting to the expulsion of Russian diplomats, Russian Foreign Ministry Spokeswoman Maria Zakharova characterized the move as the loyal lip service to the UK and accused London of imposing on Europeans a decline in relations with Russia.
Skripal, who also worked for UK intelligence, and his daughter have been in hospital in a critical condition since March 4 and are being treated for exposure to what the UK experts believe to be the A234 nerve agent. The UK side claimed it was a Novichok-type nerve agent, which was developed in the Soviet Union.
Skripal and his daughter are being treated for exposure to what the UK experts believe to be the A234 nerve agent allegedly similar to Novichok. UK Prime Minister Theresa May has accused Russia of orchestrating an attack on the former intelligence officer, and expelled 23 Russian diplomats as a punitive measure.