The 27-year-old's match fee is also to be withheld pending the outcome of the inquiry, with the detail of the case still unclear
Sri Lanka have suspended batsman Danushka Gunathilaka from all forms of cricket while an investigation is held into an alleged code of conduct breach.
Gunathilaka has hit twin 50s during his country's ongoing Test match against South Africa in Colombo and his suspension will kick in at the game's conclusion.
The 27-year-old's match fee is also to be withheld pending the outcome of the inquiry, with the detail of the case still unclear.
"Sri Lanka Cricket (SLC) decided to suspend Danushka Gunathilaka from all forms of international cricket for breaching the 'Player Code of Conduct', pending inquiry," Sri Lanka Cricket said in a statement.
"The decision to suspend the player was taken following an initial inquiry conducted by Sri Lanka Cricket, after the team management reported that the player have violated the 'Code of Conduct'."
Sri Lanka need five more wickets to beat South Africa, with the guests requiring 244 more runs to win.