An upstart political party has taken aim at Google for banning it from using its logo or the word "opium" in its online ads, while another activist group is fighting with Facebook over claims of censorship.

Search engine giant Google has been accused of restricting political debate by a new political party campaigning for the legalisation of marijuana.

The Hemp Party, which will field Senate candidates in the federal election, is furious that Google has blocked the party from using a marijuana leaf logo or the word opium in its advertisements.

“This is censorship by stealth,” James Moylan, the Hemp Party’s national campaign director, told Crikey. “We’re not selling stoner gear — we’re engaging in serious political lobbying on a serious issue.”

Moylan argues Google’s approach limits the discussion of drug law reform and violates the implied constitutional right to freedom of political communication. He’s threatening to take on the internet behemoth in a Castle-style legal challenge after the federal election. “It’s really unreasonable behaviour,” he said. “No Australian company would behave in this arbitrary and bloody-minded way.”

The Hemp Party’s ads and logo, which Google has banned

Google AdWords — which sells sponsored links on Google — informed the party yesterday that an ad containing the word opium had been disapproved because it violated Google’s Illegal Drugs and Psychoactive Substances policy. The company explained its decision in an email yesterday:

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According to Moylan, Google previously banned a Hemp Party ad featuring the party’s registered logo because it contains an image of a marijuana leaf.

Similar issues are likely to flare up repeatedly in coming years as activist groups and political parties become increasingly reliant on online platforms such as Google, Twitter and Facebook to spread their message.

Crikey reported yesterday that the Facebook page for protest group Burger Off, which is campaigning against the construction of a McDonald’s restaurant in Melbourne’s Dandenong Ranges, had been censored. Facebook told the group a post had been removed because it contained “hateful language” — an argument the group denies.

The group also claims Facebook pulled down other entries and threatened to block an administrator for calling on supporters to post comments on McDonald’s US and Australian Facebook pages.