LONDON, May 15 (Xinhua) -- The Scottish parliament on Tuesday refused to give its consent to Britain's key Brexit legislation -- EU Withdrawal Bill.

MSPs (Members of the Scottish Parliament) rejected the British government's bill by 93 votes to 30.

The governing party at Holyrood, the Scottish Nationalists Party (SNP), won backing from Labour, Liberal Democrats and Greens MSPs to inflict the blow to British Prime Minister Theresa May's government.

The vote meant SNP leader Nicola Sturgeon's move to oppose proposals on post-Brexit power sharing was passed by the Scottish parliament, which fears May's current proposals would restrict its powers.

At the heart of the day's vote are fears among many Scottish politicians that a key section of May's legislation dealing with the return of devolved powers from the European Union after Brexit represents a "power grab" by Westminster.

Scottish Brexit minister Mike Russell told MSPs they needed to defend the progress which has been made in the 20 years of devolution.

"It is the job of MSPs to ensure that progress on devolution made over 20 years is not cast aside because of a Brexit which Scotland did not vote for and which can only be damaging to our country," he said.

He told MSPs: "Today the challenge of Brexit, or rather the challenge of the proposed power grab by the UK government under the guise of delivering Brexit, puts our devolved settlement at risk."

Political commentators said although the vote is not binding on May's government, it presents the British prime minister with the dilemma of either imposing a power-sharing plan on Holyrood, or attempting to avert a crisis by putting forward concessions.

Scottish Conservative constitution spokesman Adam Tomkins denied there was a power grab, describing today's Holyrood decision as baffling. Tomkins said in Wales, where there is also a devolved government, the administration has backed a deal.

The Scotsman newspaper commented: "The vote takes the UK into uncharted constitutional territory marking the first time that Holyrood has knocked back legislation that Westminster intends to press ahead with anyway."

The Guardian newspaper said Conservative Party sources suggested May is likely to push the legislation through the House of Commons without Scottish parliament's consent.

The EU Withdrawal Bill aims to transfer all existing European legislation into domestic British law and is regarded as one of the most important pieces of Brexit legislation.

The Scottish parliament and Westminster have been at loggerheads for months over how to manage EU powers that will return to Britain after Brexit, including over state aid for industry, genetically modified crops policy, fishing quotas and farm subsidies, after ministers in London made a series of concessions brokered by the Scottish Conservatives.

Both sides agree those policies should operate uniformly across Britain. May's government says it will consult the Scottish parliament on all changes to those policies, trying to seek agreement, while Sturgeon has decided that consultation is not enough, and insists that her government should be given the legal power to block any changes it disagrees with.