Private equity group Blackstone has launched a joint bid with China National Bluestar for Australian agricultural chemical maker Nufarm, the Financial Times reported. The deal is seen as evidence of Blackstone's growing ties with China. Earlier this year it sold a US$3 billion holding to the Chinese state investment agency and then went on to take a 20% stake in Bluestar, which makes chemicals. Last month Blackstone and Bluestar's US$2.7 billion bid for Nufarm was rejected, but they are now understood to be willing to pay around US$4 billion. On Thursday, Nufarm suspended trading of its shares after announcing it had been notified of a potential takeover offer, although it did not name the parties involved. If the deal is successful, it will be the first time a private equity firm has partnered with a Chinese company in a big overseas acquisition.