Prosecutors said they raided a total of nine places, including the federation and the Korea Racing Authority, as well as homes of officials related to the matter. They declined to specify whose homes they raided.

The office of Park Sang-jin, chief of external affairs at Samsung Electronics and president of the equestrian federation, was also included on the raid list, according to prosecutors.

It was the first time in eight years that the headquarters of the country's largest conglomerate has been raided by prosecutors.

Prosecutors here have been looking into allegations that Samsung sent 2.8 million euros ($3.1 million) to a company owned by Choi in Germany, under the name of a consulting arrangement, to fund her daughter's equestrian training.

The raid came five days after prosecutors questioned an executive director at the group, identified only by his surname Kim, to bear witness to suspicions that Choi collaborated with a former presidential secretary to push local companies to donate some tens of billions of won to two nonprofit foundations. There have been allegations that the money was then illegally funneled to Choi, who is suspected of meddling in state affairs and amassing profits based on her ties to the president.

Choi is currently being interrogated by the prosecution while under custody, as a local court issued a warrant to formally arrest her last week.

President Park Geun-hye issued two apologies over the scandal since late last month, but failed to allay public outrage.

Her approval ratings plunged last week to 5 percent and 11.5 percent, the lowest figures ever compiled by Gallup Korea and Realmeter, respectively, the pollsters said. The previous Realmeter record was held by late president Roh Moo-hyun, whose approval rating once hovered at 12.6 percent.

Tens of thousands of citizens took to the streets over the weekend, demanding her resignation. Another massive rally is scheduled to take place in downtown Seoul on Saturday. (Yonhap)