Liverpool’s owners have said the club is not for sale, but they are willing to consider proposals from outside investors amid speculation that a Chinese-backed consortium wants to buy a stake.

The stance was restated following reports that financial conglomerate Everbright was working with an investment company to buy a substantial stake in Liverpool, valuing the club at more than £700m.

The consortium, which may bring in other investors, wants to work with the current owner, John W Henry, rather than buy the entire club, according to Sky News. An agreement would be one of the biggest investments by a Chinese company in a Premier League club and comes after a surge of interest from investors in China.

The 18-time English champions and Fenway Sports Group, which owns Liverpool, are said to have received no offer for a stake and are not in active talks with a potential investor. But an informal approach has not been ruled out from the consortium, which is yet to finalise plans, or its advisers.

Everbright, which is backed by the Chinese state, is said to be working on its offer with PCP Capital Partners, an investment company known for brokering deals for Middle Eastern clients.

PCP is headed by Amanda Staveley, who helped arrange the sale of Manchester City to Sheikh Mansour bin Zayed al-Nahyan, a deal that helped the former leapfrog Liverpool to become one of England’s wealthiest football clubs. Sheikh Mansour sold a 13% stake in Manchester City to Chinese investors last year.

Staveley helped Barclays raise more than £3bn in funding from Sheikh Mansour during the financial crisis and is suing the bank for £721m of what she claims are unpaid fees.

She has been involved in a bid for Liverpool before. In 2009, Staveley was the conduit between the club and a Kuwaiti group that considered buying it from the then owners Tom Hicks and George Gillett.

Fenway, which also owns the Boston Red Sox baseball team, bought Liverpool for £300m in 2010 and pledged to return the club to the top of English football, following what was then a 20-year gap since the club last won the top flight. However, despite heavy spending on players, Liverpool’s form has been erratic and they finished eighth in the Premier League last season.

Everbright’s interest in Liverpool surfaced a day after one of the club’s co-owners said Fenway had no intention of selling the club.

“We’ve said it before and I’d like to say it again: this club is not for sale. If someone wants to write us a letter saying they want to buy the club, then it will get put in the garbage,” Tom Werner told the Liverpool Echo.

But Werner said he and Fenway’s co-founder John Henry were prepared to consider approaches about taking a minority stake in Liverpool.

“We actively pursue commercial opportunities, which in turn helps us invest in the squad and win football matches. These commercial discussions can be complex and we’ve said in the past, under the right conditions and absolutely with the right partner, we could look at some small investment stake in the club,” he said.

Chinese businesses have been busy investing in European football clubs since the president, Xi Jinping, said he wanted China to become a world footballing power. West Bromwich Albion, Aston Villa and Wolverhampton Wanderers have been bought by Chinese investors in the past few months.