The resignation on Thursday of British Prime Minister Boris Johnson will have no impact on the security guarantees Finland has received from Britain, Defence Minister Antti Kaikkonen (Cen) told Yle.

"The mutual commitments between Finland and the UK are not personal, but are between states, and in this respect, such changes in personnel, which occur in politics from time to time, do not affect relations or commitments between the states," Kaikkonen said.

Johnson quit as Conservative Party leader on Thursday following a series of damaging scandals, but pledged to stay on as Prime Minister until a successor is chosen.

Finland's President Sauli Niinistö signed a joint security declaration with Johnson in Helsinki in May, which Niinistö described at the time as a "big step forward" for co-operation between the two countries.

Finland's application for Nato membership will also be unaffected by the turmoil in British domestic politics, as Britain ratified Finland's application for membership on Wednesday.

"There is strong cross-party support in the UK for this cooperation with Finland and very strong and clear support for our membership of Nato," Kaikkonen added.