LONDON/ZAPORIZHZHIA, Ukraine, Sept 28 (Reuters) – Russian-installed officials in four occupied regions of Ukraine reported huge majorities of votes in favour of joining Russia as the United States planned a U.N. resolution condemning the referendums as shams and Moscow remained defiant.

Europe was investigating what Germany, Sweden and Denmark said on Tuesday were attacks that caused major leaks from two Russian energy pipelines. But it remained far from clear who might be behind the leaks.

Hastily arranged votes took place over five days in the eastern regions of Donetsk and Luhansk and in Zaporizhzhia and Kherson to the south that together make up about 15% of Ukrainian territory.

Vote tallies from complete results on Tuesday in the four provinces ranged from 87% to 99.2% in favour of joining Russia, according to Russia-appointed officials. The head of the upper house of the Russian parliament said the chamber might consider annexation on Oct. 4.

“The results are clear. Welcome home, to Russia!,” Dmitry Medvedev, a former president who serves as deputy chairman of Russia’s Security Council and an ally of President Vladimir Putin, said on Telegram.

Within the occupied territories, Russian-installed officials took ballot boxes from house to house in what Ukraine and the West said was an illegitimate, coercive exercise to create a legal pretext for Russia to annex the four regions.

“This farce in the occupied territories cannot even be called an imitation of a referendum,” Ukrainian President Volodymyr Zelenskiy said in his nightly video address on Tuesday.

The United States will introduce a resolution at the United Nations Security Council calling on member states not to recognise any change to Ukraine and obligating Russia to withdraw its troops, U.S. envoy Linda Thomas-Greenfield said.

“Russia’s sham referenda, if accepted, will open a pandora’s box that we cannot close,” she said at a council meeting.

Russia has the ability to veto a resolution in the Security Council, but Thomas-Greenfield said that would prompt Washington to take the issue to the U.N. General Assembly.

“Any referenda held under these conditions, at the barrel of a gun, can never be remotely…