MANILA, Philippines—Senators can endorse commercial products, an election regulator said Friday, dismissing calls for sanctions against premature campaigning for the 2010 presidential election.

The Commission on Elections said it was "less than noble," but within the bounds of freedom of expression for legislators to endorse products and services including weight loss and skin-whitening pills.

While the Constitution bans premature campaigning, the senators cannot be considered presidential candidates before they actually file their candidacy papers, it added.

Those endorsing commercial products have included Vice President Noli de Castro and a number of senators who are his presumptive rivals for the presidency.

"The Commission recognizes that there is a need to quell the less-than-noble practices complained of by the petitioner," Comelec Chief Jose Melo said in his ruling.

"However, as the law stands, these practices cannot be restrained or punished," he said, urging the petitioner, Senator Miriam Defensor-Santiago, to instead file a bill to punish the practice.

Santiago had asked the official election watchdog to sanction her colleagues for premature campaigning.