A man and a woman have been detained by specialist officers at Heathrow Airport on the suspicion of "the commission, preparation or instigation of acts of terrorism".
It's understood that the couple were arrested after arriving on a flight into the airport.
Police are searching two separate addresses in East London as part of their inquiry.
"The arrests form part of an investigation into travel to Syria in support of alleged terrorist activity."
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Increasingly cloudy with drizzly rain tonight. A cloudy start on Monday but brightening up with plenty of sunny spells in the afternoon.
The grass pollen risk will rise to high during warm, dry weather.
Cloudy with patchy rain and drizzle this evening. Mild tonight, then dry with plenty of sunny spells tomorrow.