A case has been registered and an investigation has been initiated, Delhi Police said.
Pro-Khalistan slogans were found scrawled on the walls of at least five Delhi Metro stations in the run-up to the G20 Summit, police said.
The G20 summit will be held in the national capital from September 9 to 10. It is expected to be attended by over 30 heads of state and senior officials from the European Union, invited guest countries, and 14 heads of international organisations.
"It is a law and order situation. We will cooperate with the Delhi Police," a Delhi Metro Rail Corporation official said as quoted by news agency PTI.
A case has been registered and an investigation has been initiated, Delhi Police said, adding that CCTV footage is also being scanned to get leads in the case.
"Sikhs For Justice (SFJ) also released raw footage of Delhi Metro stations which were defaced with pro-Khalistan slogans," Delhi Police was quoted as saying by news agency ANI. "Suspected SFJ activists defaced multiple Metro stations in Delhi - from Shivaji Park to Punjabi Bagh - with pro-Khalistan slogans."
Ahead of the G20 summit, Delhi Police is monitoring social media to prevent the spread of rumors and inflammatory content, identify criminal elements, and focus on security at malls, markets, and religious sites in the city.
All borders into the national capital will be sealed to prevent unauthorised entry, but normal vehicular and public movement will be allowed, Delhi Police said.
A total of 80 teams of doctors and 130 ambulances will also be on standby to handle any medical emergencies during the summit. In a review meeting recently, Delhi Lt Governor VK Saxena was informed that 60 deputy commissioners of police (DCPs) have been assigned specific tasks related to the summit.