Police arrested Atsunobu Usuda after the incident on Saturday morning - which took place less than 10 days before a parliamentary election in Japan.

The 49-year-old was charged with obstructing the performance of official duties - but additional charges can be added later.

No injuries were reported after the alleged attack, which took place before 6am local time.

Five or six firebombs were thrown at the headquarters of the Liberal Democratic Party (LDP), reported as Molotov cocktails, before the man attempted to drive into the nearby grounds of Prime Minister Shigeru Ishiba's office, police said.

After crashing, he then allegedly tried to throw what appeared to be a smoke bomb, before his arrest.

TV footage showed dozens of plastic containers in the vehicle.

It was not immediately apparent what the motive behind the incident was, with Japanese media reporting that social media posts believed to have been Usuda's showed him complaining about the cost of running for office in his country - implying he had political ambitions.

The media also quoted unidentified sources claiming Usuda had taken part in protests against nuclear plants.

The LDP declined to comment on Saturday's attack.

This comes around two years after then-prime minister Shinzo Abe was assassinated while making a speech during an election campaign.

Mr Abe was shot dead using a handmade gun, with the killer claiming to resent him because his mother gave all the family's money to the Unification Church and he saw the political leader as affiliated with the religious group.

The LDP has suffered a blow to its popularity recently due to a ballooning money scandal involving questionable funding and suspected tax evasion.

Some politicians lost the official backing of the party but decided to run as independents in the 27 October election.

The party recently chose a new leader, Mr Ishiba, hoping to present a fresh image, but polls show its popularity is plummeting nonetheless.

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However, it's unclear if the LDP will lose its grip on the lower house given the splintered opposition.

In the ongoing campaign, some candidates have even been heckled, which is relatively rare in Japanese culture.

The LDP has ruled Japan almost continuously over recent decades and it is credited with leading Japan as it became an economic powerhouse from the aftermath of World War II.