SIMFEROPOL, Ukraine (AFP) — Lawmakers in Crimea voted to join Russia yesterday, escalating tensions in Ukraine as the new Government in Kiev said it wanted to sign an EU agreement “as soon as possible” and the US announced sanctions to punish Moscow.

Pro-Russia lawmakers said they would also put the question of secession from Ukraine to a referendum on March 16, as the worst East-West crisis since the cold war deepened with Russian forces maintaining their grip on the region.

The motion was passed by 78 out of 86 MPs in favour and was immediately condemned by Ukrainian authorities as “illegitimate”, while the large ethnic Tatar minority in the Black Sea peninsula said they would boycott the vote.

Gunmen at an improvised checkpoint on Crimea’s regional border with the rest of Ukraine also blocked a group of 40 unarmed military observers from carrying out an inspection mission requested by Ukraine’s Government.

A spokeswoman for the Organisation for Security and Co-operation in Europe, Natacha Rajakovic, said they were “prevented from entering Crimean territory” and would stay in a hotel in nearby Kherson to “decide on next steps”.

A Western diplomatic source said that the gunmen, who did not identify themselves, were “very professional, very well-trained — this was not some militia”.

Wider diplomatic efforts to defuse the crisis also appeared to stall, with a second round of talks between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov in two days ending with no agreement.

With an executive order, US President Barack Obama also approved possible visa bans and property sanctions against people seen as “directly involved in destabilising Ukraine, including the military intervention in Crimea”.

The measures were “in response to Russia’s ongoing violation of Ukraine’s sovereignty,” the White House said.

European Union leaders at a hastily convened emergency summit in Brussels also pushed for Russia to opt for dialogue and de-escalation, while warning that sanctions were in the offing should Moscow refuse a diplomatic solution.

“We have got to make sure we get Russia and Ukraine talking to each other,” said British Prime Minister David Cameron.

Invited to attend the summit in a strong symbolic gesture, Ukraine’s interim premier Arseniy Yatsenyuk accused Russia of continued provocation around Ukrainian bases in Crimea.

“This is not only a Ukraine-Russia crisis, it is a crisis in Europe,” said Yatsenyuk, who took over just last month after former pro-Moscow President Viktor Yanukovych fled to Russia following three months of deadly protests.