The Scottish Government wants Scotland to remain in the EU without adopting the euro currency or opening borders and with a cut-price contribution to the budget.
But Flemish nationalist MEP Mark Demesmaeker, part of the SNP-affiliated European Free Alliance, said membership negotiations will be more difficult if Scotland insists on EU opt-outs.
Flemish unionist MEP Jean-Luc Dehaene, a former prime minister of Belgium, said there is already opposition to the UK’s budget rebate, and there is no opt-out of the euro or the Schengen free travel area for new EU members.
The Scottish Government said Scotland’s existing relationship with the EU as part of the UK – including its opt-outs – would form “the basis for agreement” in post-independence membership negotiations.
Demesmaeker said: “We are fully pro-European. We want to stay in the Eurozone. We are not really in favour of opt-outs but it is for Scotland to decide if they want to ask for them. Asking for opt-outs is always making life a little bit more difficult. It’s more difficult for the British and Danish because of this.
“We don’t believe in Europe à la carte, but there could be good reasons for Scotland to ask because they are enjoying these opt-outs now.”
Demesmaeker’s Belgian New Flemish Alliance party fights for self-determination alongside the SNP and Welsh nationalists Plaid Cymru in the European Parliament.
Dehaene’s Christian Democratic and Flemish party promotes Belgian unity, and is part of the centre-right European People’s Party in the European Parliament.
Dehaene said: “It is clear that unless there is another [UK in/out] referendum, the rest of Great Britain would stay a member and the position of Scotland would be up for discussion.
“If they choose independence and put themselves out of the member state, the future is not evident.
“Also, in political terms because you have similar discussions in other member states – Spain, Italy and Belgium – a number would have some concern over how to treat the precedent. I don’t know how Belgium would react, because we have also this problem.
He added: “In the Parliament there is already an opposition to the UK’s budget rebate. When Schengen was brought in, opt-outs were given to Great Britain and Ireland, but when you come in as a new member you have to accept the treaty as it is. For new members, there is no opt-out for the monetary union. It’s up to the EU to decide if Scotland will be a new member in that sense.”
A Scottish Government spokeswoman said: “There will be negotiation on the specific terms of our continued membership, but these discussions will take place from within the EU.
“In the transition period immediately after a vote for independence in 2014, Scotland will still be part of the UK, so by definition will still be part of the EU while these negotiations take place. As such, Scotland would enter discussions with our share of the existing relationship between the UK and the EU, including existing opt-outs, as the basis for agreement.”
There is no mechanism for Scots’ EU citizenship to be removed, she added.