The latest bus burnings came just hours after hundreds of people marched in silence through the rundown suburb of Clichy-sous-Bois on Friday to commemorate the deaths of Bouna Traore and Zyed Benna which triggered the riots a year ago.
A police source in the Seine-Saint-Denis suburb said two hooded men boarded one bus in front of a train station in in the early evening and ordered around 15 passengers and the driver to get off before setting it alight.
The second bus was attacked in a similar way by two armed men in another area of the suburb, a local official said.
At least five buses have been attacked in poor suburbs around the capital since Sunday and police have said violence could spiral out of control once again.
The fresh violence came despite the deployment of 4,000 extra policemen to prevent a repeat of last year's disturbances.
Hundreds of people had marched earlier in the day to commemorate accidental deaths of two young immigrants in an electricity substation last year.
Soumeya Ata, who travelled to Clichy-sous-Bois from the distant southwestern town of Pau to attend the commemoration, said: "You can really feel the anger and the suffering of the people who live in Clichy-sous-Bois."
Around 500 mainly young people from immigrant families marched on Friday.
Traore and Benna were killed after being electrocuted when they hid in an electrical substation while fleeing from the police, according to witness reports.
Their deaths triggered the worst riots to hit the French capital in nearly 40 years.
The mayor of Clichy lays a
wreath at the substation
Marchers, many sporting T-shirts with the slogan "Dead for Nothing", passed the electrical substation where the two died and their families wept as they laid flowers at its gate.
Organisers called for quiet reflection to mark the tragedy, although some television crews pulled out after their staff were threatened by local youths.
Tensions remain high in France's rundown suburbs, where poor job prospects, racial discrimination, a widespread sense of alienation from mainstream society and perceived hostile policing incited a wave of violence 12 months ago.
Rafika Benguedda, a 21-year-old student and marcher, said: "Nothing has changed."
An upsurge in attacks on buses on the eve of the anniversary prompted Nicolas Sarkozy, the interior ministor, to draft in extra police late on Thursday after transport chiefs warned they could pull services if the arson continued.
Law and order could again play strongly in 2007 presidential elections in which hardliner Sarkozy, the conservative frontrunner, is likely to run.
The 2005 riots were the worst in the Paris area since student riots in 1968.