Anbang Insurance, the highly acquisitive Chinese group, has been adding to its stake in China Vanke amid a rare public battle over corporate ownership at the nation’s biggest homebuilder by sales.

The Chinese insurer, which bought the Waldorf Astoria hotel in New York for $1.95bn last year and failed in a recent bid to buy Portuguese lender Novo Banco, increased its stake in China Vanke from 4.5 per cent to 7 per cent over the last three weeks, according to regulatory filings in Hong Kong.

Anbang’s move adds to the intrigue surrounding China Vanke, after the chairman of the company attacked stakebuilding by a lesser-known insurance and property group called Baoneng.

Wang Shi, the charismatic, mountain-climbing founder of China Vanke, said the acquisition of a more than 20 per cent stake by companies linked to the Baoneng group “could ruin China Vanke’s greatest asset”, which he said was “trust in the company’s brand”.

Baoneng, which is controlled by another tycoon, Yao Zhenhua, hit back saying that it was law-abiding, had contributed “huge value” to society and its clients, and believed in “the power of the market”.

Shenzhen-listed shares of China Vanke have jumped by nearly 70 per cent over the past month, giving it a market capitalisation of around $40bn, as the Baoneng-linked entities overtook state-owned China Resources group to become the developer’s biggest shareholder.

China Vanke asked for trading in its shares to be suspended on Friday and on Sunday it said it was working on a “material asset restructuring”, which some analysts speculate could be designed to dilute Baoneng’s holding.

While mergers and acquisitions are on the rise in China, executives rarely fight for corporate control in the public arena, preferring to secure approvals from officials behind the scenes before acting.

“Generally Beijing frowns on public displays of confrontation in the markets,” said Andrew Collier of Orient Capital, an equity research house in Hong Kong. “This is new and significant because we’re seeing a very visible and well-respected company that now seems to be in play.”

China’s property sector has come under increasing stress in the past couple of years as the economic slowdown has hit developers with large debts and those in smaller cities particularly hard.

As well as being the largest, analysts view China Vanke as one of the country’s best developers in terms of the quality of its projects and its relatively strong financing position.

“The credit position of Vanke is very solid,” said Kaven Tsang, an analyst at Moody’s, the credit rating agency. “Its sales performance has been strong this year... it has managed a low debt leverage.”

Baoneng affiliate Shenzhen Jushenghua has disclosed that it borrowed money to fund part of the acquisition of the China Vanke shares and analysts have questioned whether it would have the financial firepower to take over the company, even if it could secure approval to do so.

Mr Collier of Orient Capital said that despite the war of words, it was not clear if the stakebuilding was driven by commercial or political motives and that it was therefore uncertain how the dispute would turn out.

After criticism of his opposition to Baoneng’s equity purchase, Mr Wang, who is a patron of the World Wildlife Fund and has studied at the universities of Cambridge and Harvard, took to social media on Monday night to clarify his position.

“An enterprise is a group of people who are bound together by philosophy,” he wrote on Weibo, China’s version of Twitter. “If the corporate philosophy changes, it would be a disaster. That’s just a matter of fact, not a value judgment.”