LONDON (AP) - Canadian doctors have been advised not to use a batch of 170,000 doses of swine flu vaccine while authorities investigate reports of allergic reactions among recipients, drug maker GlaxoSmithKline PLC said Tuesday.

Authorities routinely monitor vaccines for any signals of problems, such as the allergic reactions that do occur, rarely, every year.

Company spokeswoman Gwenan White said that GlaxoSmithKline advised medical staff in Canada last week to refrain from using one batch of the vaccine while they look into reports that that it might have caused more allergic reactions than normal.

"One batch has seen a slightly increased rate of anaphylaxis," she said. Anaphylaxis is life-threatening type of allergic shock.