South Korea’s government said on Wednesday that Moscow had expressed “deep regret” over the incident that prompted South Korean jets to fire warning shots near a Russian military plane, but a Russian spokesman countered that his country had not formally apologized.

The contrasting — if not quite contradictory — statements, and Russian objections to parts of the South Korean account, illustrated the tension over the most serious confrontation in years between the two nations.

On Tuesday, a Russian military jet flew twice into South Korea’s territorial airspace, officials in Seoul said, and when it did not respond to radio warnings, South Korean planes fired shots to ward it off. Russia denied any violation of another country’s airspace.

But on Wednesday, Yoon Do-han, a spokesman for the South Korean president, told reporters that a Russian military attaché in Seoul had conveyed Moscow’s “deep regret” about the incident and had said that the Russian plane mistakenly deviated from its flight plan. He did not describe the Russian statement as an outright apology.