Central Sydney has filled with a sea of protesters for the "Bust the Budget" march.

Organisers estimated up to 15,000 people joined the rally, which started at Town Hall and proceeded along George Street and up Market Street.

Thousands of people marched through Sydney CBD protesting the government's budget. Credit:James Alcock

Police figures put the number of marchers at 6000.

The protest was peaceful and police said there had been no reported incidents.