TOKYO (Kyodo) -- Yuichiro Tamaki, head of the small but influential opposition Democratic Party for the People, on Monday admitted to an extramarital affair revealed in a tabloid magazine report, offering an apology.

The report, released the same day, came after the DPP quadrupled its seats from seven to 28 in the House of Representatives election late last month, increasing its influence as the ruling coalition parties failed to obtain a majority.

The online edition of Flash weekly magazine reported that Tamaki was seen entering hotels in Takamatsu, Kagawa Prefecture in western Japan with a Takamatsu tourism ambassador. Tamaki said the report was mostly accurate.

In a DPP meeting later in the day, lawmakers affirmed that Tamaki should continue as party leader after he said he would ask his colleagues whether he should resign as chief of the DPP.

"I sincerely apologize not only to my family, but to the people who have placed their hopes in me," Tamaki, elected from a Kagawa constituency, said at a press conference.

He added that he wants to "give back" to the people by doing his work diligently, and said he would not quit as a lawmaker if his supporters forgive him.

The DPP has begun talks with the ruling Liberal Democratic Party and its coalition partner, the Komeito party, aiming to reach policy-by-policy agreements to avoid a political stalemate.

At the forefront of the DPP's policy push is to increase people's incomes at a time of rising prices, including by raising the current 1.03 million yen ($6,700) threshold for people to start paying taxes.