PKR president Anwar Ibrahim has congratulated DAP's Vivian Wong for retaining the Sandakan seat for Pakatan Harapan in today's by-election.

However, Anwar said the coalition must not become complacent.

"This win shows that the people still have strong support for Harapan.

"However, the Harapan leadership can't become comfortable with this win and must instead continue to work hard to ensure that the people's economic standing is protected at all levels," he said in a statement tonight.

He added they should also mobilise efforts to help Prime Minister Dr Mahathir Mohamad make his "Shared Prosperity" vision for the country a reality.

Wong retained the Sandakan seat today, with a 11,521 vote majority against PBS' Linda Tsen and three independent candidates.

Tsen only managed to secure 4,491 votes.