LUCKNOW, Jan. 9 -- Dense fog across Uttar Pradesh on Thursday disrupted road, rail and air traffic, with Lucknow airport seeing widespread flight cancellations and delays. An IndiGo flight from Delhi to Lucknow was cancelled, while the Riyadh-Lucknow service arrived nearly two hours late. More than 10 flights were delayed at airports across the state, including Gora- khpur. Lucknow Airport received a diverted IndiGo flight (6E 2334) from Delhi to Varanasi after the aircraft was denied landing at Varanasi's Lal Bahadur Shastri International Airport due to poor visibility. The diversion added to congestion at Lucknow as fog continued to impact operations across the region. At Varanasi airport, four flights were cancelled because of dense fog. The cancelled services included Air India Express flight IX 1023/2547 (Mum- bai-Varanasi-Mumbai) and IndiGo flights 6E 714/499 (Bengaluru-Varanasi-Bengaluru), 6E 6447/6570 (Mumbai-Varanasi-Mumbai), and 6E 401/6044 (Chennai-Varanasi-Chennai)....