Dec 16 (Reuters) - Foreigners were net buyers of Japanese shares in the week to Dec. 10 on hopes that the Omicron coronavirus variant would be less disruptive to the global economy than initially feared. They purchased 239.69 billion yen ($2.10 billion) worth of Japanese stocks last week, their first weekly net buying since Nov. 12, data from Japanese exchanges showed. Overseas investors bought derivatives of 513.08 billion yen but sold 273.39 billion yen in cash equity markets. Meanwhile, cross-border investors sold Japanese bonds of 784.2 billion yen last week after five straight weeks of net buying, finance ministry data showed. Japanese shares tracked a Wall Street rally last week as investors cheered some optimistic comments from a top U.S. official on the Omicron variant. read more Sentiment was also boosted after Pfizer (PFE.N) and partner BioNTech (22UAy.DE) said a three-shot course of their COVID-19 vaccine was able to neutralise the Omicron variant in a laboratory test. read more The Nikkei share average (.N225) gained 1.5% last week and the Topix index (.TOPX) rose 0.9%, snapping two consecutive weeks of decline. Both benchmarks are set for a second consecutive week of gains this week as shares advanced on Thursday after the U.S. Federal Reserve said it would end its pandemic-era bond purchases in March and begin raising interest rates as much as three times next year. read more Japanese investors purchased a net 196.2 billion yen worth of cross-border equities last week, marking a third straight week of net buying. They also bought overseas bonds of 449.4 billion yen. ($1 = 114.1500 yen)