Germany-listed shares in the company were up 12.6% at 0926 GMT, giving the group an equity market value of about 8.7 billion euros (£7.4 billion).

The shares had gained 14% on Wednesday, after a report that life sciences tools maker Thermo Fisher Scientific Inc had approached Qiagen about a potential deal.

"The Supervisory Board and the Management Board ... are starting discussions with interested parties," the company said on Friday.

"These discussions aim to explore potential strategic alternatives that could provide greater value creation opportunities than the already strong stand-alone growth prospects for the company," it added.

There company said there was no guarantee these discussions would lead to a deal.

A spokesman declined to elaborate on Monday.

Potential annual cost savings of $250 million, in addition to a better revenue growth potential in a larger group, could sway Qiagen's board to support a takeover, analysts at brokerage Berenberg said on Monday.

The company's larger peers include Agilent, Danaher, and Siemens Healthineers.

Qiagen Chief Executive Officer Peer Schatz stepped down in October after the company posted preliminary third-quarter sales below estimates due to weaker-than-expected developments in China.

Schatz, a company veteran of 27 years with a 1.3% stake in the group, had been seen as a champion of Qiagen's independence.

The maker of diagnostic kits for cancer and tuberculosis has also previously said it would stop developing next-generation genome sequencing machines and collaborate with industry leader Illumina.

(Reporting by Ludwig Burger and Patricia Weiss; Editing by Edmund Blair)