Dentsu Inc. said Tuesday it will put off the acquisition of Aegis Group PLC, a major British advertising agency, by a month until March 28 because a Chinese regulator needs more time to complete its screening.

Japan's largest ad agency and Aegis both operate in China and need the Chinese authority's approval to go ahead with the planned takeover. Proceedings in China have been delayed by the Lunar New Year holiday, according to Dentsu.

The firm announced the purchase of Aegis last July for £3.16 billion — about ¥400 billion, based on the prevailing currency rates at the time.

The yen has fallen sharply against the pound since, but the acquisition cost will not increase significantly, Dentsu claims, because it made forward currency arrangements.

Proceedings involving corporate takeovers by Japanese companies in China are taking longer at a time when Sino-Japanese relations have become seriously strained due to the row over the Senkaku Islands.