The pound slumped Monday on reports British Prime Minister Theresa May was ready to take the country out of the European Union in a so-called "hard Brexit".

Sterling's weakness sent London's FTSE 100 index to a fresh record high, while eurozone and Asian stock markets retreated.

"It would appear that the main catalyst behind this (pound) sell-off is speculation that UK Prime Minister Theresa May will set out tomorrow the UK government’s position" on negotiating Brexit, said Michael Hewson, chief market analyst at CMC Markets UK.

Sterling on Monday plunged to $1.1986, its lowest level since October's "flash crash" that had sent it to a 31-year low of $1.1841.

"Weakness in sterling has been the primary means by which the FTSE 100 has notched up its record-breaking run," said Chris Beauchamp, chief market analyst at IG trading group, after the index hit a record high at 7,354.14 points following a string of peaks over the past few weeks.

The pound has fallen sharply since Britain voted in June to exit the European Union, pushing up share prices of multi-nationals on the FTSE index of 100 firms including the likes of energy giants Shell and BP.

In the eurozone Monday, Frankfurt's DAX 30 index was down 0.6 percent around midday and the Paris CAC 40 shed 0.5 percent compared with Friday's close.

Most Asian stock markets retreated also Monday as investors nervously await US President-elect Donald Trump's inauguration speech Friday, having been left disappointed at his lack of detail on economic policy at a news conference last week.

- 'Great thing' -

May on Monday won endorsement from Trump over her Brexit course, with him saying that Britain leaving the EU would "end up as a great thing", adding in an interview with The Times newspaper that he would work for a trade deal with post-Brexit Britain "quickly and done properly".

Trump's comments did little to reassure investors, however, following reports in British media over the weekend that May is planning to announce a hard line on Brexit in a major speech on Tuesday.

"Wind the clock back twelve months and it was concerns about the Chinese economy that was prompting a significant period of volatility in both currency markets, and stock markets," analyst Hewson added Monday.

"As we head into 2017, while concerns about the Chinese economy have taken a back seat, it is Brexit as well as the impeding inauguration of Donald Trump... that is currently front of mind, in what looks set to be another choppy week for financial markets."

World equities surged after Trump's election win in November on bets his plans for big infrastructure spending and tax cuts would fire the world's top economy, and in turn the global economy.

But the lack of any definitive plan at last week's briefing left many scratching their heads and worrying he might not fulfill his promises.

In Asia on Monday, Tokyo's stock market ended one percent lower as a pick-up in the yen against the dollar hit exporters, traders said.

- Key figures around 1030 GMT -

London - FTSE 100: UP 0.1 percent at 7,341.93 points

Frankfurt - DAX 30: DOWN 0.6 percent at 11,558.07

Paris - CAC 40: UP 0.5 percent at 4,896.44

EURO STOXX 50: DOWN 0.7 percent at 3,302.45

Tokyo - Nikkei 225: DOWN 1.0 percent at 19,095.24 (close)

Shanghai - Composite: DOWN 0.3 percent at 3,103.43 (close)

Hong Kong - Hang Seng: DOWN 1.0 percent at 22,718.15 (close)

New York - Dow: FLAT at 19,911.40 (close)

Pound/dollar: DOWN at $1.2062 from $1.2190

Euro/dollar: DOWN at $1.0593 from $1.0639

Dollar/yen: DOWN at 114.28 yen from 114.53 yen

Oil - West Texas Intermediate: UP 16 cents at $52.53 per barrel

Oil - Brent North Sea: UP 10 cents at $55.55