Scottish First Minister Nicola Sturgeon warned Sunday it would be a mistake to hold Britain's European Union membership referendum in June. British Prime Minister David Cameron hopes to finalise a renegotiation of the UK's terms of membership at the European Council meeting on February 18 and 19.
An in-or-out referendum on Britain's membership of the bloc must be held by the end of 2017, with commentators believing it could come this year.
Sturgeon said holding it in June would be "disrespectful" to the Scottish, Welsh, Northern Irish and London mayoral elections, which are taking place in May.
Speaking about a possible June vote, Sturgeon told BBC television: "I think it would be a mistake for David Cameron.
"Two reasons why I would not be in favour of a June referendum.
"The Scottish election is in May, indeed the Welsh, Northern Irish, London elections are in May.
"To have a referendum campaign starting in parallel would be disrespectful to those important elections.
"The second reason is I think it would be better for David Cameron... if he does get a deal at the February European Council: to leave more time between that deal and the point of decision."
Cameron wants to renegotiate Britain's terms of membership, then recommend that the UK remains in the 28-country bloc on that basis.
Sturgeon said: "One of the big problems I see for the In campaign at the moment is that as far as David Cameron is concerned it is very much focused on these narrow issues of renegotiation, when in actual fact, if the In campaign is going to prevail, this is going to have to become a positive in principle campaign about why it is better for the UK to stay within the European Union."
Foreign Secretary Philip Hammond has ruled out a referendum in July or August.
Cameron wants a referendum campaign lasting at least three months.