Police, hunting the bombers who targeted three underground trains and a double-decker bus last Thursday, have warned that the forensic search for clues is a painstaking process that could take time.

• 警方正在追捕上周四制造了三处地铁和一辆双层巴士爆炸的凶徒，警方警告说，追查线索是艰苦的过程，需要时间。