BEIJING — Vietnam said on Friday that it would conduct live-fire naval exercises off its coast next week, a step that escalated a long-running dispute with China over territory in the South China Sea that both nations claim.

The naval maneuvers follow an exchange of sharp statements on Thursday. Vietnam claimed that China had harassed a seismic survey boat, damaging a research cable trailing behind it, and China demanded that Vietnam halt oil-exploration activities in the area.

In an announcement on its Web site, Vietnam’s state-run Northern Maritime Safety Corporation said that nine hours of naval exercises would be held on Monday off the country’s central coast, and it warned other vessels to avoid the area. This is the first time that the government has publicized a live-ammunition drill, The Associated Press reported.

The diplomatic flare-up is the most serious confrontation this year in a territorial dispute that also involves the Philippines, Malaysia and Taiwan. All five countries have competing claims to parts of the South China Sea bed, which may hold valuable oil and mineral deposits. Arguments over the territory have continued for years, and the nations signed a 2002 accord that committed them to show restraint in disputed waters.