Combat dolphins in Crimea will be transferred to the Russian navy in a final act of humiliation for the Ukrainian army.

The combat dolphin programme in the peninsula will be "preserved and redirected" to the Russian navy, an employee at the Sevastopol oceanarium told Russian news agency RIA Novosti.

The animals will be used to "search and locate enemy divers" and carry "spy equipment" for the Russian navy, which has seized control of all military bases and ports in Crimea, consolidating the Kremlin's control over the region it officially annexed last week following a controversial referendum.

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Yesterday, US President Barack Obama told reporters the annexation is Crimea is not a done deal and expressed concern about Russia's territorial ambitions.

Speaking at the Hague, President Obama said the US rejected the "notion that a referendum sloppily organised over the course of two weeks" would "be a valid process" and the West does not recognise the annexation of the peninsula.

Mr Obama described the deployment of Russian troops along the Ukrainian border as "an effort at intimidation" echoing concerns expressed by Ukraine's Foreign Minister, Andriy Deshchytsya, who warned the risk of military intervention remains high.

On Monday, world leaders of the G7 cancelled a planned G8 summit in Russia in an effort to isolate President Putin until the Kremlin "changes course". Instead, world leaders of G7 nations will now meet in Brussels without Russia in June.

In a statement, the group reiterated their support for Ukraine's sovereignty and territorial integrity and warned the G7 is "ready to intensify" sanctions against Russia's wider economy if Mr Putin does not de-escalate tensions in the region.

So far, the West has abstained from imposing tougher sanctions such as arm embargoes and bans on energy imports, which would affect the heart of the Russian economy.

Russia's Foreign Minister, Sergei Lavrov, who was initially dismissive of the move and described the G-8 as an "informal club", said the Kremlin is keen to maintain diplomatic contacts.

“The Russian side continues to be ready to have such contacts at all levels, including the top level,” Mr Putin’s spokesman, Dmitry Peskov, told Interfax news agency.