U.S. President Barack Obama urged presumptive Republic presidential nominee Mitt Romney to release more of his tax returns, in an interview with a U.S. network released Saturday.

Obama conducted the interview with Univision, a leading U.S. Spanish-languange television network amid the Summit of the Americas in Colombia. The anchor asked Obama, who released his tax information on Friday for the 12th consecutive year, if Romney should do his own part.

"I think that it's important for any candidate in public office to be as transparent as possible, to let people know who we are, what we stand for, and you know, I think that this is just carrying on a tradition that has existed throughout the modern presidency," Obama replied.

According to the released tax returns by the White House, the U. S. First Family reported adjusted gross income of 789,674 dollars for last year, and they paid 162,074 in taxes. Obama's effective federal income tax rate is 20.5 percent.

The White House also used the occasion to highlight Obama's position in a tax system reform which is to "ask the wealthiest Americans to pay their fair share".

Obama's campaign has been pushing multimillionaire Romney to release more of his prior tax returns. Obama re-election campaign spokesman Ben LaBolt said earlier they "will challenge Romney" to release his tax returns.

Romney campaign spokeswoman Andrea Saul said Romney has already released his 2010 return and an estimate of his 2011 income and taxes and "he will release his full 2011 return when it's filed."

The former Massachusetts Governor requested an extension on Friday to file for last year's tax returns. His campaign estimated he earned about 21 million U.S. dollars last year with the tax liability at 3.2 million U.S. dollars.

His campaign has said he will file his tax returns before the 2012 election.

This week marked Obama and Romney's campaign shifting into general election gear, as Romney's main GOP rival Rick Santorum quit his race and cleared Romney's path to the Republican nomination.