The government must take more seriously the threat of a nuclear weapon being exploded in space by a rogue state, MPs have warned.
The Defence Select Committee said the resulting radiation pulse could disrupt power and water supplies, UK defence and satellite navigation systems.
Its chairman, Tory MP James Arbuthnot, said an attack was "quite likely".
The committee is urging ministers to invest in more "hardened" technology to cope with such an event.
It looked at the threat to the UK's technological infrastructure from "electromagnetic pulse" (EMP) events in space, which could also include the eruption of solar flares.
The committee found the government was "somewhat complacent" about the risks to technology, such as the destruction of computer chips, which could put defence systems out of action.
Mr Arbuthnot told BBC Radio 4's Today programme: "The defence really is to build up the resilience of the electronic infrastructure by, over a period of time, replacing the incredibly delicate and vulnerable systems and chips and connections that we now have with the more hardened chips and connections and systems that are available at a not very expensive price, as you're doing your routine maintenance."
On the possibility of a nuclear missile being fired into space and exploded, he said: "I personally believe that it's quite likely to happen. It's a comparatively easy way of using a small number of nuclear weapons to cause devastating damage.
"The consequences if it did happen would be so devastating that we really ought to start protecting against it now, and our vulnerabilities are huge."
Mr Arbuthnot added: "it would actually have a far more devastating effect to use a nuclear weapon in this way than to explode a bomb in or on a city. The reason for that is it would, over a much wider area, take out things like the National Grid, on which we all rely for almost everything, take out the water system, the sewage system.
"And rapidly it would become very difficult to live in cities. I mean within a matter of a couple of days.
"I wish the government would address this with rather more energy and cohesion and focus. I think sooner rather than later."
Currently a severe "space weather" event would most likely be considered an "emergency" under the Civil Contingencies Act 2004 and require help from the armed forces.
But the committee called for a clearer picture of who has responsibility in such an event.
The report insisted such threats should be considered by the National Security Council and civil contingency planners, with standards of protection developed for industries most in danger.
Conventional defence alone could not protect against the threat, it said.
In February last year a large solar flare erupted, disrupting flights over Pacific, but the bulk of the material emitted by the Sun passed by Earth.
The committee said sudden fluctuations in the magnetic field caused by weather in space or nuclear attack, could wipe out electricity and GPS, used by the military and financial markets.
It added: "Space weather is a global threat and may affect many regions and countries simultaneously."
This, the report said, meant countries should work together, but also that there was no guaranteed safe place from where help could come.
The report also urged the Ministry of Defence to plan for the loss or degradation of satellite-based communications systems in case they are damaged by severe space weather.