By Pavel Polityuk and Natalia Zinets
KIEV (Reuters) - Pro-Ukrainian activists prevented repairs to sabotaged power lines leading to Crimea on Monday, keeping the Russian-annexed peninsula starved of electricity for a second day and tensions between Moscow and Kiev high.
Ethnic Tatars and members of Ukrainian nationalist battalions stopped Ukrainian engineers fixing four pylons blown up by unknown attackers over the weekend in Kherson, a region of the Ukrainian mainland controlled by Kiev.
If "we get confirmation that we have access, we can start restoring the lines as soon as tomorrow," said Vsevolod Kovalchuk, the acting head of state power supplier Ukrenergo, which has said it is holding talks with the activists.
Russian engineers began laying undersea cables from southern Russia to Crimea earlier this year to allow the contested territory, which is home to around 2 million people, to draw all its power from Russia by 2020.
But for now, the peninsula which Russia seized last year depends on Ukraine for at least 70 percent of its electricity. Russian officials said they would speed up work on the first phase of the undersea cable project, which will ease dependence on Ukraine, so it could come online by the middle of next month.
Ukraine's current power supply deal with Crimea expires on Dec. 31. Energy Minister Volodymyr Demchshyn said on Monday it was up to the Ukrainian political leadership to decide if the contract would be extended next year.
TATAR DISCONTENT
Russia's annexation of Crimea plunged relations between Kiev and Moscow into a crisis deepened by a rebellion by pro-Russian separatists in eastern Ukraine.
One Russian senator described the blasts as an "act of terrorism".
Mustafa Dzhemilev, a senior Crimean Tatar politician, said the process of restoring power to Crimea could start only after "political prisoners" on the peninsula were released.
The annexation was opposed by many Tatars, a Turkic-speaking Muslim community with a long history in Crimea, and they have since held numerous protests to complain of discrimination and intimidation which they say is meant to silence dissent.
The peninsula's pro-Kremlin leadership denies a crackdown is underway.
In September, Tatar activists on the mainland set up road blocks on the two main routes leading into Crimea at the start of what they said was an economic blockade aimed at dramatising the plight of their Tatar brethren living on the peninsula.
The obstacles have prevented road cargo from reaching Crimea from Ukraine, and on Monday Prime Minister Arseny Yatseniuk recommended the government officially suspend cargo shipments to the peninsula following a similar statement by President Petro Poroshenko.
The activists deny they blew up the pylons, which also triggered blackouts in parts of Ukraine's Kherson. While preventing any work that would help restore electricity to Crimea, they said they would allow repairs to lines supplying mainland Ukraine.
Dmitry Peskov, a Kremlin spokesman, said Russia hoped Kiev would take "vigorous steps" to restore Crimea's power supplies.
Russia's Energy Ministry said emergency electricity supplies had been turned on for critical needs in Crimea and that mobile gas turbine generators were being used. Sergei Aksyonov, the Kremlin-backed head of Crimea, declared Monday a non-working day because of the emergency situation.
Russia's annexation of Crimea triggered punitive Western sanctions on Moscow, which a diplomat told Reuters on Sunday would stay in place until at least July 2016.
Russia's Interfax news agency reported on Monday that three people had been detained in Moscow for hanging a blue and yellow Ukrainian flag on the facade of a Stalin-era skyscraper.
A Russian court in September convicted a Ukrainian man of helping try to paint his country's national flag on the same skyscraper in protest against the Kremlin's foreign policy and sentenced him to two years and three months in jail.