David Cameron has pledged the Government will do everything it can to safeguard the Westcountry's vital rail link despite the threat from flooding.
The Prime Minister was responding to a call for assurances by Gary Streeter, Tory MP for South West Devon, that the region would not be cut off again after the mainline was recently swept away causing severe disruption.
The resilience of the rail network is now seen as even more important following the loss of the city's air link, and the vulnerability of the motorway to closure.
Transport Secretary Patrick McLoughlin is said to be aware of the "unacceptable disconnection" between Plymouth and the rest of the country, and has promised to treat moves to protect the rail link as an urgent priority.
Network Rail, which is responsible for the track, has been carrying out a study aimed at shoring up the vulnerable mainline, which was shut by flooding.
Raising the issue with the Prime Minister during his weekly question time in the Commons, Mr Streeter said: "I know he is aware of the extreme flooding suffered in the Westcountry in November and December last year, impacting on many homes and businesses and sweeping away the rail link between the west country and London, leaving us cut off for several days.
"Will he please ensure that our Government take every step necessary to improve the resilience of this vital rail link so that we never get cut off again?"
Responding, Mr Cameron said: "I am well aware of how bad the flooding was and I went to Buckfastleigh to see how badly the town had been flooded for myself.
"I know the Secretary of State for Transport has discussed the recent flooding with Network Rail's chair and chief executive, and he will visit the area soon to look at this.
"We are working with Network Rail to improve the resilience of the overall network and we will do everything we can to ensure that these important services are maintained, even when they are challenged by floods such as those we saw last year."
Speaking afterwards, Labour MP for Plymouth Moor View Alison Seabeck said: "I can't emphasise enough to government ministers just how urgent the situation is down in the South West.
"We really need to see the Secretary of State in Plymouth within the next four weeks with a timetable for action."