New Delhi, Nov. 13 -- A political confrontation has erupted between between the Bharatiya Janata Party (BJP)-led Delhi government and the Aam Aadmi Party (AAP) over the alleged "deaths of thousands of fish" in the Yamuna, with the two sides trading allegations over pollution in the river days before the Chhath festival. Delhi irrigation and flood control minister Parvesh Verma on Thursday alleged that groups of people were "deliberately dumping" dead fish into the river to create panic ahead of Chhath and malign the BJP government. He said his department had been instructed to file an FIR and identify those involved. In a letter dated November 12, accessed by HT, an executive engineer of the irrigation and flood control department's civil division-4 approached the SHO of Sonia Vihar police station, seeking an FIR and an investigation into what it described as the circulation of fake news on social media about chemicals being sprayed into the Yamuna. "Some unidentified individuals are spreading fake information on social media platforms, alleging that chemicals are being sprayed into the Yamuna thereby disturbing aquatic life," the letter stated. Verma also alleged that dead fish were dumped into the river a day after the launch of the Yamuna cruise service, in an attempt to disrupt the festival. He said an investigation would establish whether those involved had links with AAP workers. Hitting back, AAP Delhi chief Saurabh Bharadwaj accused the BJP government of trying to divert attention from pollution in the river. He said the deaths had exposed the government's claims of cleaning the Yamuna. The political exchange came amid concerns over pollution in the Yamuna affecting water treatment. The New Delhi Municipal Council (NDMC) said on Wednesday that a sudden rise in pollution levels in raw Yamuna water had led to curtailed production at the Sonia Vihar water treatment plant. A Delhi Jal Board (DJB) official had told HT on Wednesday that ammonia levels of around 1.5-2 parts per million (ppm) were being recorded at the Yamuna's inlet point, against a disruption threshold of 0.9 ppm. However, the DJB said on Thursday that ammonia levels near the Wazirabad barrage were around 0.5 ppm, within the manageable range, and that water treatment and supply operations were continuing normally....