Finnish Foreign Minister Pekka Haavisto has said it would be "useful" for Sweden and Finland to launch joint Nato membership bids.

But he said that no fixed date had been set for any potential application.

The comments came as Nordic media reported the countries could launch a simultaneous bid to join the security bloc next month.

Stockholm and Helsinki have long pursued policies of military neutrality to avoid conflict with regional powers.

But during a visit to Sweden earlier this month, Finnish Prime Minister Sanna Marin said "everything had changed" when Russia attacked Ukraine and told reporters that Helsinki must to be "prepared for all kinds of actions from Russia".

Her comments coincided with the publication of a security report that warned Finland's membership of Nato could result in "increased tensions on the border between Finland and Russia".

Finnish newspaper Iltalehti reported on Monday that the two countries' leaders could meet in the week of 16 May to announce the bid during a state visit to Sweden by Finnish President Sauli Niinisto.

Finland shares a 1,340km (830 miles) border with Russia, and Kremlin spokesman Dmitry Peskov has stressed that Moscow would have to "rebalance the situation" with its own measures if the Nato bid went ahead.

And there have been some reports that Russia had started to move military equipment towards the Russian-Finnish border, although US officials said they had seen nothing to confirm that.

But Swedish outlet Aftonbladet reported that the US and UK have agreed to provide security support during the application process, citing government officials.

US defence sources told the outlet that Sweden and Finland would be treated as de-facto members of the security alliance for the duration of the application process.

The UK and US support would reportedly include an increased number of troops in the Nordic nations, further intelligence co-operation, assistance in combatting cyber threats and an increased presence of Nato warships in the Baltic sea.

Last week Sweden's Foreign Minister Ann Linde said a wide-ranging security review being carried out by Stockholm will be completed by 13 May, rather than 31 May as initially planned.

She noted that with Finland's analysis now complete "there is now a lot of pressure" to urgently publish the report, and her party, the Social Democrats, are expected to drop their traditional opposition to joining the bloc.

Russia sees Nato as a threat to its security, and before the war in Ukraine Russian President Vladimir Putin demanded that the bloc removed its forces from Eastern European member states.

However, Russia's invasion has had the opposite effect, with Nato bolstering its forces in Eastern Europe and traditionally neutral countries now on the verge of joining the bloc.

Public sentiment in both Sweden and Finland towards Nato membership has changed dramatically since Russia launched its invasion over two months ago.

In Finland, opinion polls show that public support for joining bloc has climbed from 28% in February to 68% last month.

Meanwhile, 57% of Swedes now favour NATO membership, up from 51% in March.