(ShareCast News) - Although its shares climbed steadily on Monday, engineer WS Atkins has refused to comment on reports that it has been approached by US peer CH2M Hill over a possible $4bn merger. The Times said privately owned CH2M, which has worked with the UK company on projects such as the Thames Tideway super sewer, has held talks with Atkins at a senior level, although it was unclear what stage the discussion has reached.Last year Atkins suggested it and others in its sector were in line to benefit from plans by the UK government and US President Donald Trump to increase infrastructure spending.Atkins told media that it was its policy not to comment on rumours and speculation.The UK Takeover Panel obliged companies to make an almost immediate response to such reports if there is any truth in them, indicating talks involving Atkins may have been terminated at an early stage.However, despite the silence, Atkins shares continued to climb over the day, standing more than 6% higher by late afternoon at 1,490p.