The proposed takeover of 3Com by Bain, the private equity firm, and Huawei, the Chinese telecommunications equipment maker, came under further pressure in Washington after lawmakers called on the administration to block the acquisition of the US technology group.

A non-binding resolution introduced by Ileana Ros ­Lehtinen, the most senior Republican on the House foreign affairs committee, said the transaction in its current form threatened national security and should not be approved by the inter-agency panel that investigates foreign transactions. Under the terms of the $2.2bn deal, Huawei will take a minority stake in 3Com.