US President Barack Obama said rich Americans and companies should pay more taxes beyond last week's accord to avoid the spending cuts and tax increases known as the fiscal cliff as Congress seeks other ways to pare the deficit.

"Spending cuts must be balanced with more reforms to our tax code," Obama said in his weekly radio and Internet address. "The wealthiest individuals and the biggest corporations shouldn't be able to take advantage of loopholes and deductions that aren't available to most Americans."

Congress passed legislation just after the fiscal cliff deadline of Dec 31 that raised taxes on the wealthiest Americans while extending tax cuts for lower incomes and delaying automatic spending cuts until March 1. Markets rallied in response to the agreement, even as Obama and congressional Republicans face a new struggle over raising the US government's debt ceiling.