Germany is ramping up security at airports, train stations and ports after government intelligence revealed the country could be attacked at the end of November.
The interior minister, Thomas De Maiziere said there were “clear indications” that a terrorist attack was being planned.
According to reports in Germany, an unnamed country was said to have warned officials of the potential danger.
De Maiziere has been quoted as saying the government had received information about “sustained efforts” by Islamic extremists to launch attacks.
The heightened security means business travellers could face delays at airports and train station both in the UK and in Germany.
The interior minister said the extra security across the country would remain in place until further notice.
The German government also confirmed that two parcel bombs sent from Yemen to the United States had been intercepted in the last few days, one of which was picked up in the UK.
German airline Lufthansa, which flies a number of flights everyday out of Heathrow to German airports, would not say if it was stepping up its own security, simply stating: "[We] are aware of the German Government warnings.
"Whilst airport security controls are the responsibility of the authorities and the Federal Police, Lufthansa nevertheless remains in close contact with the relevant authorities and is cooperating fully.
"Since 11 September 2001, security levels in air traffic and at Lufthansa have remained on a high level."