Bidders emerged for allergy-testing company Phadia and diagnostic test-maker Gen-Probe, according to The Wall Street Journal.

Laboratory equipment company Thermo Fisher Scientific is a leading contender for privately owned Phadia, and is involved in the auction for Gen-Probe, the newspaper reported in its online edition.

Phadia could fetch as much as $3 billion in a sale, while Gen-Probe has a market capitalization of $3.8 billion.

Other bidders for Gen-Probe include Novartis, and Life Technologies Corp, the newspaper said.

Gen-Probe, Phadia, Thermo Fisher declined to comment. Life Technologies and Novartis, which has a partnership with Gen-Probe, could not be immediately reached for comment.

Last month, Gen-Probe hired Morgan Stanley to seek a buyer for the company, sources familiar with the situation said.