LONDON?British police were on a manhunt Monday to catch jewel thieves who pulled off a smash and grab raid on luxury stores right next to the Bank of England.

The hooded gang of four broke into London's Royal Exchange, a heavily-protected shopping center packed with luxury boutiques, before smashing open display cases at South African diamond jewelers De Beers and Swiss watchmakers Omega.

Police said the jewels stolen late Saturday had an estimated retail value of ?380,000 ($600,000, ?460,000).

"The thieves broke through a padlocked gate then smashed the shop windows with sledgehammers, before taking diamond jewelry and watches from the window displays," a City of London Police spokesman said.

"No other stores were targeted and the gang left in the same red BMW they arrived in. The thieves wore hooded tops and balaclavas.

"The force is treating this incident very seriously."

He said officers were now trawling through security camera footage and appealed for witnesses, saying that although the City financial district is quieter on weekends, several bars and clubs were open in the area.

A security guard at the center, who did not want to be named, said: "A BMW turned up at the back entrance, four men jumped out and managed to get inside the building somehow.

"It's looking as though whoever has done this has been targeting the shops for a long time."

The robbery is the latest in a spate of raids at jewelers in London.

Earlier this month the gang behind Britain's biggest jewelry theft was jailed.

Four men were convicted for the ?40-million ($62-million, ?49-million) Graff diamond robbery last August.

Both the De Beers and Tiffany and Co. stores were raided in the new Westfield shopping complex in London earlier this year, with the raiders making off with an estimated ?2-million worth of jewels.

And the Mozafarian store in west London was targeted last August, when thieves stole more than ?1-million worth of gems.