Prime Minister António Costa said in The Hague on Tuesday that it would be "great" if a solution to Turkey's current veto on Finnish and Swedish membership of NATO could be found by the time of the Madrid summit in a two weeks' time.

"It is clear that if, by the Madrid summit, the reasons that lead Turkey to block the entry of Finland and Sweden can be overcome, great," he told the press, after an informal meeting of some of the government members of NATO member countries with NATO's secretary-general in the Netherlands.

Costa said an agreement before the June 29th and 30th summit in the Spanish capital "would be a great message of strength", and that "NATO remains united, but is also strengthened by the accession of two new member states".

If this does not happen in the two weeks remaining before the summit, "surely it will be possible to overcome [the dispute] with time," Costa said, adding that the current dispute, "being related to terrorism, must be taken seriously".

The head of government insisted that "the Madrid summit is fundamentally important" for the alliance to "approve the new strategic plan for the next 10 years," as well as "the investment plan and the reinforcement of NATO funding" in the next decade, stating that, along with the consolidation of the unity of the partnership, "this is the main theme" of the summit.

Costa was speaking at the end of a working dinner for NATO heads of state and government members with the Secretary-General of NATO, Jens Stoltenberg. The dinner was hosted by the Prime Ministers of the Netherlands, Mark Rutte, and Denmark, Mete Frederiksen.

The meeting, held at the official residence of the Dutch head of government, was also attended by the prime ministers of Belgium, Poland, and Latvia, as well as the President of Romania.

Russia's military aggression against Ukraine led the two Nordic countries, both EU member states, to decide to break with a long-standing policy of military non-alignment and apply for membership of the North Atlantic Treaty Organisation (NATO).

However, Turkish President Recep Tayyip Erdogan vetoed the membership of Sweden and Finland, whom he accuses of supporting Kurdish militants considered terrorists by Turkey, namely the Kurdistan Workers' Party (PKK). Erdogan is demanding that Stockholm and Helsinki change their policies.

Stoltenberg, who described the concerns of Turkey as "legitimate", has led diplomatic efforts to overcome this blockade "as soon as possible" so that Sweden and Finland can soon become full members of NATO.

NATO's secretary-general, who visited the two Scandinavian countries this week, said the Madrid summit was never a deadline for a political decision on Swedish and Finnish membership, but admitted he hoped "progress" would be made.

At the summit later this month, NATO leaders are expected to adopt the alliance's new strategic plan for the next decade, including strengthening deterrence and defence, addressing transnational threats such as cybersecurity and climate change, and deepening partnerships with democratic allies in Europe and Asia in a new geopolitical context triggered by Russia's invasion of Ukraine.