Sweden’s governing Social Democrats have reiterated their support for a Kurdish group that Turkey claims is a terrorist organisation, in a move that kept the party in power but could complicate attempts to stop Ankara blocking the country’s bid to join Nato.

After a knife-edge vote, the government survived an attempt by the rightwing opposition to dislodge the justice minister. The government would have resigned if the confidence vote against the minister had succeeded.

But the centre-left government only won the vote after the Social Democrats confirmed their support for an unusual agreement with Amineh Kakabaveh, an independent MP of Kurdish heritage who is a kingmaker in the parliament. The deal professes extensive support for Kurdish groups in northern Syria.

Turkey is blocking Nato applications by Sweden and neighbouring Finland. Turkish president Recep Tayyip Erdoğan has called both countries “guesthouses” for terrorists, and has focused particularly on the People’s Protection Units (YPG), a Kurdish militia in Syria.

Many western countries backed the YPG, which helped defeat Isis in north-east Syria. But Turkey views the militia as a direct threat because of its close ties to the Kurdistan Workers’ party (PKK), which is recognised by the EU and US as a terrorist organisation.

The Social Democrats’ deal with Kakabaveh, reached in November to make sure that party leader Magdalena Andersson became prime minister, is highly supportive of the YPG and an associated political group, the Democratic Union party (PYD).

“That freedom fighters who fought or sympathise with YPG or PYD are classed by certain state actors as terrorists is unacceptable . . . The Social Democrats intend to deepen their co-operation with the PYD,” the November agreement said, according to Kakabaveh’s Facebook page.

Tobias Baudin, party secretary of the Social Democrats, said on Tuesday: “The agreement we reached in November still applies . . . we Social Democrats always stand by the agreements we make, you can always trust that.”

Kakabaveh said Baudin had reassured her recently that Sweden would not compromise with Turkey on Nato.

Sweden’s centre-right opposition, which wants to join Nato, had offered to help the government survive and support the bid to join the security alliance if it dropped the justice minister, Morgan Johansson. He was facing criticism over crime and gang violence.

The opposition accused the government of harming the Nato bid by siding with Kakabaveh.

Kakabaveh told the Financial Times on Monday that the Swedish government was allowing “a tyrannist, a despot, an Islamist regime” to decide who is in government in Sweden.

Sweden’s approach of playing party politics with such issues contrasts with Finland, which has sought to launch a charm offensive to win over Turkey — dangling the prospect of buying Turkish drones and increasing arms sales, while stressing its tough approach on terror.

“In the current context, this is likely to make it more difficult for the Swedish government to find a creative diplomatic compromise. This situation may also become fodder for domestic politics in Turkey, which could further inflame the situation,” said Paul Levin, director of the Stockholm University Institute for Turkish Studies.