Labour MEPs have said the European Union must stick to its principles on the justice, rights, freedom and security when it comes to assessing which countries are fit for admission.
The Commissioner for European Neighbourhood Policy and Enlargement Negotiation, Johannes Hahn, presented the 2015 EU Enlargement Package to MEPs this week, saying the Commission "will continue to focus our efforts on the rule of law", including judicial reforms, and tackling organised crime and corruption.
He also says there will be a "strong focus on fundamental rights", including freedom of expression and fighting discrimination, notably against the LGBTI community and Roma, and on the functioning of democratic institutions and public administration reform.
Richard Howitt MEP, Labour's European Parliament spokesperson on foreign affairs, and Socialists and Democrats (S&D) Group co-ordinator, said:
"The Commission has our support in emphasizing the rule of law and fundamental rights in its commitment to open negotiating chapters 23 and 24 - those on justice, freedom and security - with Turkey and fYR Macedonia in particular.
"If the EU wants new cooperation that should involve new money, not reassigning monies already earmarked for the Instrument for Pre-Accession.
"To do this denies the long-term investment in the interests of the countries of the Western Balkans and of Turkey, and risks undermining cohesion between refugees and host communities in situations which are already volatile in the short-term.
"If we say we are concerned about a return to tensions and nationalism in the Western Balkan region, Europe must be careful not to risk provoking it ourselves.
"On Turkey, we welcome the idea of opening new, relevant negotiation chapters. We also consider Turkey as a central partner in facing the migration crisis, as well as a major player in solving the conflict in Syria.
"However, we express our grave concern about violations of rights of assembly, of press freedom and of minority rights, particularly during the electoral period.
"It is also important that the Enlargement Commissioner does all he can to encourage Turkey to restore the peace process with the Kurds, and for him and the whole European Union to make all efforts to support reconciliation on the island of Cyprus.
"Both of these objectives are first and foremost in the interests of all the peoples directly affected themselves, but also in the interests of advancing accession negotiations with Turkey too.
"The refugee crisis must not distort EU enlargement policy. The refugee crisis must be dealt with its own right but so must enlargement countries."
Afzal Khan MEP, member of the European Parliament foreign affairs committee, and S&D Group spokesperson for Bosnia and Herzegovina, added:
"EU enlargement policy is an important tool and we need to accelerate its process to strengthen social, political and economic stability and democracy in the Western Balkans region.
"The refugee crisis and the challenges it brings must not be allowed to threaten the Western Balkans reform progress and to trigger old conflicts. As the main transit area, the Western Balkans cannot be forgotten nor left alone.
"We must use this challenge to work even more closely together, demonstrating solidarity and putting our values into practice.
"I am pleased, that after years of the stalemate in Bosnia and Herzegovina's accession process, some progress has been achieved and the country is slowly moving forward again.
"This momentum needs to be intensified and the EU must assist in this."