Ukraine on Monday halted the delivery of goods to Crimea in a move set to ratchet up tensions with Russia, with the annexed peninsula already reeling after explosions on power lines left some 1.6 million people without electricity.

Kiev has also threatened a tit-for-tat ban on food imports from Russia in a dispute connected to a free trade agreement between Kiev and the EU that is set to come into force from January, while the interior minister has suggested cutting off power to Crimea totally.

The new spike in tensions between Moscow and Kiev -- which have been at daggers drawn since Moscow snatched Crimea in March 2014 -- comes despite a dip in fighting in the conflict in the east of Ukraine thanks to a shaky truce between government troops and rebels the West says are armed and backed by Russia.

"The Ukrainian government temporarily suspends the movement of goods between Ukraine and Crimea at the initiative of Prime Minister Arseniy Yatsenyuk," Ukraine's government said in a statement.

Yatsenyuk made the announcement during a government meeting after President Petro Poroshenko proposed that his government discuss suspending the delivery of cargo to Crimea.

Ukraine's Western-backed leader requested that the government "immediately establish a working group" to halt "deliveries of goods and all trade" with Crimea which still depends heavily on Ukraine for its water and electricity supplies.

As its former Soviet master, Russia strictly opposes Kiev's move to the West, trying to keep it in its orbit as Moscow says Ukraine's free trade agreement with the EU would threaten its economy.

Last week, Russia reiterated a threat to introduce a blanket ban on food supplies from Ukraine from January 1, saying Kiev's landmark agreement with the EU will damage Moscow's economic interests.

Ukraine's Prime Minister Yatsenyuk for his part said that Kiev would respond to any ban from Russia with a retaliatory measure.

"I would like to emphasise that Ukraine will respond in similar ways," he said. "Every Russian embargo against Ukraine will be followed by a Ukrainian embargo against Russia."

- Power blackout in Crimea -
The decision to halt food deliveries to Crimea comes with the peninsula already scrambling to deal with a major power crisis after its main electricity lines from Ukraine were blown up, leaving the Russian-annexed peninsula in darkness after the second such attack in as many days.

Crimea on Sunday declared a state of emergency after an explosion on Saturday in Ukraine's Kherson region bordering the peninsula cut the two working power lines heading to the territory, which produces only 30 percent of its own energy needs.

The Crimean authorities suggested Ukraine was involved in the blasts as Crimea's prosecutors opened a criminal probe.

Kiev confirmed the destruction of the power lines' towers, but the identity of the attackers is not known.

The leader of Crimea, Sergei Aksyonov, urged the residents of the peninsula "to prepare for the worst," saying the power blackout could well last until late December.
Russia is laying undersea cables to Crimea to ease dependence on Kiev and is also planning to build gas-powered power stations which would burn gas piped from the mainland.

Crimean Tatars, an ethnic group native to the peninsula who oppose Russian rule, have been holding protests at the site of the broken power lines since Saturday, calling for a blockade of Crimea to protest at the jailing of dozens of activists.

In late September, several hundred Tatars and ultra-nationalist militants organised a blockade of Ukrainian goods transported by roads to the Crimean peninsula.

Ukrainian Interior Minister Arsen Avakov suggested Monday that the government take a "political decision" and ban power supplies to Crimea altogether.

Crimea experienced several total power cuts last winter, attributed by the authorities to repairs and technical problems, but seen by residents as deliberate pressure from Ukraine.