KYIV: A senior Ukrainian official dismissed as "nonsense" on Wednesday Russia's investigation into an explosion last weekend that badly damaged a bridge linking the Russian mainland to the Crimea peninsula that Moscow has annexed.

Russian President Vladimir Putin has blamed Ukraine's security forces for the explosion and earlier on Wednesday Russia's Federal Security Service (FSB) said it had detained five Russians and three citizens of Ukraine and Armenia over the blast.

"The whole activity of the FSB and Investigative Committee is nonsense," Ukraine's public broadcaster Suspilne cited interior minister spokesman Andriy Yusov as saying when asked about Moscow's allegations on the Crimea Bridge blast.

Yusov described the FSB and Investigative Committee as "fake structures that serve the Putin regime, so we will definitely not comment on their next statements".