Prime Minister Manmohan Singh on Wednesday expressed "deep shock" over the loss of lives in the Matsyagandha train accident and said he has issued instructions to the railway ministry to provide all necessary assistance to the affected people.

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"I am deeply shocked to learn of the unfortunate Matsyagandha train accident," the prime minister said in a statement.

At least twenty people were killed and 100 injured when the Mumbai-bound Matsyagandha Express derailed after hitting two boulders between Vir and Karanja stations near Ratnagiri in Maharashtra.