Samsung has withdrawn its $6 billion takeover bid for SanDisk after Toshiba has invested $1 billion in a 30% share of the memory company.

Samsung said the reason for the withdrawal was SanDisk's declining value amid the industry downturn.

"After nearly six months of efforts to pursue a transaction with no meaningful progress, we are withdrawing our proposal to acquire SanDisk", Lee Yoon-woo, Samsung's chief executive officer, wrote in a letter to SanDisk.

"We squarely face the growing uncertainties in your business, which may continue to deteriorate in this difficult economic environment and further impact your standalone value."

In response, SanDisk said Samsung had "never contacted SanDisk regarding their proposal" and that "we believe this raises questions about the real motivations behind Samsung's offer".