LONDON (Reuters) – Russia’s defence ministry said on Friday that Ukrainian fighters and foreign mercenaries had been “securely blockaded” at the Azovstal steel plant where they have been holding out in the Ukrainian city of Mariupol. President Vladimir Putin had ordered his defence minister on Thursday to block off the vast Azovstal complex “so not even a fly can get through” rather than try to storm it. The defence ministry also said Russia had hit dozens of targets in the Donetsk and Kharkiv regions of Ukraine on Friday. In a statement, the ministry referred to the remaining fighters of Ukra…