The parliament began debating the bill at 9am on Wednesday and the vote is scheduled to take place in the afternoon, with a deadline of 4pm. 

“This is a historic but also a necessary decision to take,” Aron Emilsson, the Sweden Democrat chair of the parliament’s Committee on Defence, said at the start of the debate. “We are leaving 200 years of non-alignment behind us.” 

Six of the country’s eight parliamentary parties back joining the defence alliance, constituting an overwhelming majority of MPs. Only the Left Party and the Green Party are opposed. 

“Nothing will increase Sweden’s ability to defend itself faster than joining the defence alliance,” Emilsson said. 

MPs will vote on accepting Sweden’s accession to the alliance, and also that Sweden should sign up to the latest version of the North Atlantic Treaty which forms the legal basis of the alliance. 

Joining Nato will also require changes to two Swedish laws, the Military Operational Support Act, which governs military cooperation between Sweden and Finland, and the Immunities and Privileges Act, which governs diplomatic immunity. 

“The amendments to the law aim partly to make it easier for Sweden to request support from Nato in the form of military forces, and partly to give Nato, the national representatives and the international staff the immunity and privileges required under the agreement,” the parliament’s foreign affairs committee wrote when submitting the law to parliament.  

Sweden will not actually become a member until all 30 Nato member states have ratified its accession agreement, which so far only 28 have done, with Hungary and Turkey still holding out.

Hungary’s parliament is set to ratify Finland’s membership of Nato next Monday, Nato Secretary General Jens Stoltenberg said at a press conference in Brussels on Tuesday, but not that of Sweden. 

The news came after Turkey’s President Recep Tayyip Erdoğan last week instructed his parliament to approve Finland’s membership, while saying that a vote on Sweden’s would not take place until the country had extradited some of the people on Turkey’s list of wanted people living in Sweden. 

“There is no reason not to push ahead with both countries at the same time and that’s a message I have passed to the Hungarian foreign minister,” Sweden’s foreign minister Tobias Billström told TT after the news from Hungary. “Hungary has on repeated occasions over the past year said that they intend to ratify both Finland and Sweden.”