Syngenta (SYT) CEO Erik Fyrwald said Wednesday that he was "entirely confident" the company's $43 billion takeover by China National Chemical Corp. would close in the second quarter of this year and dismissed suggestions it would be disrupted by a third party.

Speaking with CNBC Europe television following the Swiss pesticides group's full year earnings report, Frywald said he and his colleagues would have the necessary approvals needed for the deal by the April 12 deadline set by the European Union and described talks with Brussels as "very constructive".

"We are entirely confident we are going to get this deal done in the second quarter," Frywald said "And we completely expect to have (U.S. Federal Trade Commission) approval before the April EU deadline."

Regulators in China, Europe and the U.S. will need to sign-off on the complex deal, with the FTC receiving notice of the antitrust aspects of the takeover in late January. Authorities in Australia have already granted approval for the cross-border deal.

However, persistent speculation that state-owned SinoChem could swoop in an disrupt the deal have unsettled investors for several months, even as officials in Beijing have issued stern denials.

When asked if he was concerned about a potential third party approach, Frywald was adamant: "We have regular interactions with ChemChina and I speak regularly to the chairman and he assures me that there are no talks with SinoChem and we don't see any possibility that would stop our deal closing in the second quarter."

Syngenta posted full year earnings of $2.66 billion, the company said Wednesday, on sales of $12.8 billion, both figures falling largely in-line with analysts' forecasts.

Syngenta shares closed at Sfr425.4 each in Zurich Tuesday and have risen just over 9% in the past three months.