Sweden has cleared its final obstacle to joining NATO after Hungary's parliament ratified the bid in what Sweden's prime minister called a "historic day", while other alliance members expressed relief at the move spurred by Russia's invasion of Ukraine.

NATO chief Jens Stoltenberg said Sweden would make the alliance "stronger and safer" while the United States, the main alliance power, as well as Britain and Germany welcomed Sweden's now imminent accession.

German Chancellor Olaf Scholz said that having Sweden in NATO "strengthens our defence alliance and with it the security of Europe and the world".

Russia's invasion two years ago prompted Sweden and neighbouring Finland to apply to join the trans-Atlantic bloc, ending their longstanding stance of non-alignment.

Every NATO member has to approve a new country however, and Hungary's vote on Monday ended more than a year of delays that frustrated the other 31 nations as Ukraine battled Russian troops.

Finland joined in April last year, but Sweden's bid was stalled by both Hungary and Turkey, with Ankara approving Stockholm's candidacy only last month. 

Hungary then followed, with 188 parliament members voting in favour and six far-right deputies against.

Sweden's Prime Minister Ulf Kristersson said on Tuesday it did not currently envision sending ground troops into Ukraine.

"It's not on the cards at all for the moment," he told Swedish public broadcaster SVT.

He was reacting to comments by French President Emmanuel Macron, who said on Monday that Western leaders should not rule out sending ground troops to help Ukraine defeat Russia's invading forces.

"For the moment, we're busy sending advanced (military) equipment to Ukraine," Kristersson said.

Stockholm announced on February 20 it would give Ukraine defence aid worth 7.1 billion kronor ($682 million), including artillery shells, air defence, boats, mines, torpedoes, and training for Ukrainian soldiers. 

Kyiv says it is critically short of weaponry to defend itself against Russia's invasion, now in its third year.

Kristersson said there was currently "no demand" from the Ukrainians for Western ground troops.

He said that individual NATO members had different attitudes to engaging in international affairs "and the French tradition isn't the same as the Swedish one".

Sweden contributes to international peacekeeping forces but has not engaged in combat since a war with Norway more than two centuries ago.

Russia's invasion of Ukraine on February 24, 2022, prompted Sweden and neighbouring Finland to apply to join NATO, ending their longstanding stance of non-alignment.

'Mutual good intentions'

Hungary's Prime Minister Viktor Orban had long stalled Sweden's membership but told parliament that it would "strengthen Hungary's security".

Though repeatedly saying it supported Swedish membership in principle, Hungary kept prolonging the process, asking Stockholm to stop "vilifying" the Hungarian government.

After a meeting on Friday between the nationalist Orban and Kristersson in Budapest, the Hungarian leader announced that the two had clarified "our mutual good intentions".

Hungary also signed a deal to acquire four Swedish-made fighter jets, expanding its fleet of 14 Jas-39 Gripen fighters.

Hungary's president is expected to sign the law within days. Sweden, which has been militarily neutral for two centuries, will then be invited to accede to the Washington Treaty and officially become NATO's 32nd member. 

All Baltic nations except Russia will now be part of the alliance.

It is the last piece of the puzzle in the NATO map for northern Europe

Prime Minister Giorgia Meloni of Italy, which currently presides the G7 group of industrialised democracies, said Sweden's entry "reinforced NATO for the defence of peace and freedom on the European continent".

Alongside its move into NATO, Sweden signed an accord in December that gives the United States access to 17 Swedish military bases.

The looming membership has been accompanied by a toughening of declarations by its leaders. General Per Micael Buden, commander-in-chief of the Swedish military, said in January that Swedish people "must mentally prepare for war".

"It is the last piece of the puzzle in the NATO map for northern Europe," said Robert Dalsjo, an analyst for the Swedish Defence Research Agency (FOI).

People in Sweden mainly cheered the approval.

Jimmy Dahllof, 35, said Sweden would be "safer... bringing us closer to our European neighbours".

"I am very relieved because we have been waiting so long," said Ingrid Lindskrog, a 73-year-old pensioner.

In Hungary's delay, some experts saw a strategy to wring concessions from the European Union, which has frozen billions of euros in funds because of the nationalist government's policies.

Others argued it underlined Orban's closeness to the presidents of Russia and Turkey.

For Mate Szalai, an analyst at Venice's Ca' Foscari University, Orban was simply playing to his domestic audience.

"Orban wanted to go as far as he could without causing serious problems to the trans-Atlantic community while proving that Hungary is a power to be reckoned with," he told AFP.

Many of his acts are intended to provoke Europe, Szalai added.