Stockholm  - Sweden is stepping up border security in anticipation of an invasion of dogs over the weekend, officials said Thursday.

More than 12,000 canines are expected in the country for the annual World Dog Show, which this year is taking place in the Swedish capital, Stockholm.

A police spokeswoman told radio broadcaster SR that checks would be conducted to ensure "every dog has a valid passport, vaccination certificate and other documentation."

Controls would be intensified on ferry routes from Denmark and on the Swedish side of the Oresund bridge.

Dogs without valid papers would not be allowed entry and would be turned back, along with the owners, the spokeswoman said.

If the owners insisted on entering Sweden, the officials would consider putting their animals to sleep, she added.

"This is the only way we can prevent a lot of infectious diseases coming in," she said by way of explanation. (dpa)