LONDON, March 20 (Reuters) - Sterling fell by around half a cent from a three-week high against the dollar on Monday, after a spokesman for British Prime Minister Theresa May said she would formally launch talks on leaving the European Union on March 29.
The pound, up around a third of a percent against the dollar in morning trade in London, fell back to trade as much 0.2 percent lower at $1.2366 in the half hour after the statement by May's spokesman.
Sterling also fell 0.2 percent to 86.79 pence per euro.
"We've now got a confirmation that it (the triggering of Article 50) will happen this month," said Mizuho's head of hedge fund FX sales in London, Neil Jones.
"There had been some talk May would be forced to delay it, which would have been good for the pound, but this removes any doubt." (Reporting by Ritvik Carvalho)