The investment banks involved in the process - which is unique to China, and sees bankers coach company executives on IPO-related issues - are China International Capital Corp, Bank of China unit BOCI, and Citic Securities, Syngenta said in a statement.

Sources told Reuters the IPO would value Syngenta at around $60 billion including debt, or $50 billion without.

A spokesperson for Syngenta, which is owned by ChemChina and recorded $23.1 billion in sales last year, said the firm plans to complete the IPO by the end of the first half of 2022. However, the filing of the tutoring documents indicates the float may be earlier than that, the spokesperson added.

In its statement, Syngenta described filing the tutoring documents as a "preparatory step towards a possible initial public offering" on the STAR, or Science and Technology Innovation Board of the Shanghai Stock Exchange.

An actual listing application "would require a formal submission and be subject to approvals from relevant regulators", it added.

The China Securities Regulatory Commission published the pre-listing tutoring report on its website on Monday.

State-owned ChemChina, which bought Syngenta for $43 billion in 2017, last year merged the Swiss firm with Israel's ADAMA and the fertiliser and seed business of Sinochem.

A long planned merger of ChemChina and Sinochem was approved by China's state assets regulator in March.

(Reporting by Samuel Shen and Tom Daly; Additional reporting by John Revill and Oliver Hirt in Zurich and Dominique Patton in Beijing; Editing by Toby Chopra and Jan Harvey)