Malaysian police have seized a cache of jewellery, handbags and watches worth up to $273m (£207m) in a series of raids on houses of former Malaysian prime minister Najib Razak.

Police commissioner Amar Singh confirmed that in the raids on six properties linked to Najib and his wife Rosmah Mansor, as part of the 1MDB investigation, the police seized a treasure trove of expensive goods, including 1,400 necklaces, 567 handbags, 423 watches, 2,200 rings, 1,600 brooches and 14 tiaras.

Police described it as the biggest seizure in Malaysian history. The total market value of the goods was estimated to be between $223m and $275m.

Malaysia’s former prime minister Najib Razak has denied wrongdoing. Photograph: Edgar Su/Reuters

“About 12,000 jewellery [items] were seized worth RM440m,” said Singh, adding that it had taken 16 days to count the value of them all.

The most expensive item was a gold and diamond necklace worth $1.6m.

The value of the Hermes handbags alone was $12.7m, while the watches, which were from 100 different makes including Rolex, Richard Mille and Chopard, were valued at $19m. 274 pairs of designer sunglasses, made by brands such as Cartier, Versace and Dior, were also part of the seized stash.

The raid on Najib’s properties are part of the ongoing investigation into his role into the 1MDB scandal where billions of dollars were embezzled from a government fund and fraudulently spent. $681m of 1MDB money went into Najib’s personal bank account, where it is alleged it was used to fund the lavish spending habits of Najib and his wife. He has denied responsibility.

Najib was cleared of all wrongdoing when he was prime minister in an investigation widely viewed as a cover-up, but since he lost power in May, the new government, led by 92-year-old prime minister Mahathir Mohamad, has made a renewed 1MDB investigation the priority. Mahathir said last week that they had an almost “perfect case” against Najib on charges such as bribery, theft of government funds and embezzlement. It is thought his arrest is now imminent.

About 12,000 jewellery items were seized by investigators. Photograph: Mohd Rasfan/AFP/Getty Images

The large amount of jewellery seized in the raid also puts the spotlight further on the role of Rosmah in 1MDB. She has denied putting any pressure on Najib to provide funding for her ostentatious lifestyle, but a profile in the Wall Street Journal this week claimed that her “pursuit of the trappings of wealth played a crucial part in pushing Najib’s administration deeper into graft, ultimately leading to the government’s downfall”.

The report alleged that she had been the one to set up the connection to Jho Low, the Malaysian businessman at the centre of the 1MDB embezzlement allegations, and led efforts to block the 1MDB investigations. Rosmah denies these claims.

Mahathir said this week it was hard to prove Rosmah’s involvement as her signature, unlike Najib’s, was not on any 1MDB documents.