The renovation of the Binnenhof parliamentary complex will take at least two years longer than previously planned because of extra security measures and the unresolved issue of regulating nitrogen compound emissions.

MPs and senators will have to wait until at least 2028 to move out of their temporary home on Bezuidenhoutseweg, well after the next round of elections, housing and planning minister Hugo de Jonge told parliament this week.

The delays are partly prompted by concerns raised by the national counter-terrorism and security co-ordinator in the wake of the storming of Capitol Hill in Washington by supporters of former US president Donald Trump, following his election defeat in 2020.

Heating, cooling and electricity facilities were due to be consolidated in an area beneath the underground car park. But the national security adviser now says they need to be housed in a fortified bunker, which will take 15 months to build and cause knock-on delays to other parts of the project.

Like all major construction projects, the Binnenhof renovation is also still waiting for an environmental permit, after the old regulations were scrapped the wake of the Council of State’s ruling in 2019 that they breached European law.

Building projects must now show that they keep nitrogen compound emissions below strict limits designed to protect conservation areas at all times during construction.

A new permit regime will be drawn up once the government has finalised its plans to cut ammonia emissions in agriculture through measures such as buying out livestock farmers.

But that process has been delayed until the farmers’ party BBB, which is the largest party in provincial government following last month’s elections, has finished forming local coalitions.

De Jonge did not say if the delays would increase the cost of the project, which has already stretched its budget from an original estimate of €475 million to €749 million.