Don't punish UK for Brexit: London mayor

London mayor Sadiq Khan has warned the EU it will be making a big mistake if it tries to punish the UK for leaving the European bloc.

Prime Minister Theresa May (right) and First Minister Nicola Sturgeon meet at the Crowne Plaza hotel in Glasgow, to take part in a bilateral meeting. Source: Press Association

The EU will be making a major mistake if it tries to "punish" the UK for Brexit, London mayor Sadiq Khan will warn in a keynote address in Brussels.

His comments come a day before Prime Minister Theresa May is set to invoke Article 50 and formally trigger Brexit, and are intended to put the "emotional" argument for a fair deal between the EU and the UK.

"Now is the time to be confident in the European Union and to act with confidence. There is no need - as some have suggested - for the EU to send a message, or to instil fear, by punishing the UK," he will say.

He will also call on Prime Minister Theresa May to make a gesture of goodwill when she invokes Article 50 by guaranteeing the rights of 3.3 million EU citizens in the UK.