The London-based architect group that won the first contest to redesign the National Stadium for the 2020 Olympic Games said Wednesday it is investigating similarities between its ill-fated design and design A, the winner of the second contest.

Architect Kengo Kuma's team was declared the winner of the second competition for the stadium on Tuesday, edging architect Toyo Ito. The original proposal by Zaha Hadid Architects was abandoned in July amid a public outcry over costs.

"The design team is currently reviewing the detailed designs and investigating similarities," a ZHA representative said.