Special interest groups have increased their campaign spending in California by nearly $62 million as they have skirted donation limits adopted by voters in 2000.

They instead are putting their money into independent expenditures.

The state Fair Political Practices Commission said Tuesday that 25 campaign groups had spent $63 million of the $88 million put into independent expenditures since 2001.

The groups include corporations, labor unions and Indian tribes who have spent their money supporting or opposing state candidates.

Those groups would have been able to spend just $1.3 million if they had been forced to give contributions directly to candidates.

The FPPC's staff is recommending that the commission take several steps to give voters a better idea of who is making independent expenditures. Courts have prohibited attempts to limit that spending.