Air and sea searches this evening failed to turn up any sign of eight people reportedly seen in heavy seas on a dinghy and kayaks off the Otago coast.

An eyewitness had seen the group of four kayaks and four people in a rubber dinghy head out about midday today at Kaka Point, 23km southeast of Balclutha, Rescue Co-ordination Centre New Zealand spokesman Lindsay Sturt said.

Conditions were poor with strong winds and a heavy swell.

Mr Sturt said no one had been reported missing and if the eight were caught out at sea it was likely aircraft would have located them.

"We're hoping they've actually come ashore safely, but we don't know that, of course," he said.

"We're just looking for information from anyone that might be able to tell us that these people are missing. We just haven't heard anything at all."

Anyone who was aware of the group in question was urged to contact police, who had been involved in the search.

Searchers would consider overnight how to approach the situation in the morning.