The SNP has warned Theresa May not to try to block Nicola Sturgeon's plans for a fresh referendum on Scottish independence before Britain finally leaves the EU.

The Scottish First Minister's bombshell announcement on Monday overshadowed the House of Lords vote which finally cleared the way for the Prime Minister to start the formal Brexit process.

The move drew a furious response from Mrs May who accused the SNP of "playing politics with the future of our country" with a vote that would only create "more uncertainty and division".

Her comments were seen as an indication that she will not allow the referendum to go ahead until after the Brexit process is complete - which is expected to be in the spring of 2019.

However SNP deputy leader Angus Robertson dismissed the idea that the Government at Westminster could seek to block a second independence vote.

"I just cannot see how a democratically elected UK Government will say to a democratically elected Scottish Government which was elected on a mandate to hold a referendum .... one's not going to allow a vote," he told BBC2's Newsnight.

Setting out her proposal on Monday, Ms Sturgeon said that if Scotland was to have a "real choice" the vote should take place once the terms of the Brexit deal were known but "before it is too late to choose our own course".

She will go to the Scottish Parliament next week to seek its authority to agree a "Section 30 order" - the procedure which allows it to legislate for an independence referendum - with the UK Government with a view to staging a vote between autumn 2018 and spring 2019.

The row erupted as the landmark legislation, which allows the Prime Minister to trigger the start of the Article 50 withdrawal process, completed its passage through Parliament without amendment.

Brexit Secretary David Davis hailed the outcome, saying the UK was "on the threshold of the most important negotiation for our country in a generation".

However Downing Street has indicated that the Prime Minister will not seek to invoke Article 50 until the end of the month, despite the EU (Notification Of Withdrawal) Bill completing its passage through Parliament.

EU leaders had been prepared for an announcement this week, with April 6 pencilled in as the date for a meeting of the other 27 to respond to the move - a gathering which will now be pushed back until later that month.

The Prime Minister's official spokesman played down suggestions she was delaying due to Ms Sturgeon's announcement, saying Mrs May had always said she would trigger Article 50 by the end of March.

"I've said 'end' many times but it would seem I didn't put it in capital letters strongly enough," the spokesman said.

Waiting until the last week of March would not only avoid a clash with the Dutch general election on Wednesday, but also delay the start of negotiations until after a special summit of the remaining 27 in Rome on March 25 to celebrate the EU's 60th anniversary.

On Monday night, the Lords finally backed down in their battle with ministers over their attempts to change the legislation after the Commons overturned two amendments previously backed by peers.

MPs voted by 331 to 286 to reject one amendment requiring Parliament to be given a "meaningful" vote on the outcome of the Brexit negotiations and by 335 to 287 to dismiss a second amendment guaranteeing the future status of EU nationals living in the UK.

Following the Commons votes, they were then rejected by margins of 274 to 118 and 274 to 135 in the Lords, ending peers' resistance to the Government's plans.

Labour leader Jeremy Corbyn said it was "deeply disappointing" the Government had refused to give ground but that it was "only the start of the process".

"Labour, at every stage, will challenge the Government's plans for a bargain basement Brexit with Labour's alternative of a Brexit that puts jobs, living standards and rights first," he said.

Senior Labour MSP Anas Sarwar warned that leaving the UK would be "economic suicide" for Scotland, on top of the hit it already faces because of Brexit.

Mr Sarwar, a former deputy leader of Scottish Labour, insisted the "vast majority" of people in Scotland did not want another "divisive" referendum.

"I accept that leaving the European Union is a bad thing for the United Kingdom and bad for Scotland," he told BBC Radio 4's Today programme.

"But the reality is: yes, we are going to take an economic hit from leaving the European Union, but you don't overcome that economic hit by committing economic suicide with independence."

Scotland's External Affairs Minister Fiona Hyslop said the country could not be allowed to "drift" for two years and accused Mrs May of failing to treat Ms Sturgeon's government as an equal partner in the Brexit process.

She told Today: "We have put forward compromises, we are trying to work with the UK Government, we have not had anything meaningful back.

"We can't drift for the next two years, we have to provide strong political leadership and that's exactly what First Minister Nicola Sturgeon has done."

Former Ukip leader Nigel Farage told Sky News: "It's been nine months since that joyous morning on June 24 when we realised that Brexit had won the referendum. Nine months - a full gestation - and still no delivery.

"Of course I'm disappointed. I'm pleased that we are through all these hurdles, but I'm just a bit surprised that Nicola Sturgeon's announcement should have put the Prime Minister off.

"Now that we are delaying the triggering of Article 50, what it means is that we will miss the summit of European leaders on April 6 at which Brexit could practicably have been discussed. Therefore, we've kicked it into the long grass until May."

Mr Farage added: "I'm concerned about the hesitancy, but I'm also concerned at the concessions that appear to have been made already.

"Last week in Brussels the talk was that the British were prepared to put fisheries on the table as a bargaining chip ... I'm worried about the commitment of this Government to actually get into line with what the British public asked for."

Mr Farage said the UK should be lobbying workers and companies in the remaining 27 EU nations to put pressure on their politicians to preserve free trade with Britain post-Brexit, saying: "We're so important to them, they call us Treasure Island."