8216;Bombs concealed in cargo planes unusually sophisticated8217;

Several US dailies said that the two bombs found in cargo packages were expertly constructed.

Two parcel bombs concealed inside airline cargo packages and destined for the United States were 8220;expertly constructed8221; and 8220;unusually sophisticated8221;,leading US dailies reported on Sunday.

The bombs discovered on Friday were further evidence that Al-Qaeda8217;s affiliate in Yemen was steadily improving its abilities to strike on US soil8221;,American officials were as saying by 8216;The New York Times8217;.

Authorities in Yemen on Saturday arrested a woman suspected of sending mail bombs on two US-bound flights in an alleged Al-Qaeda plot that Britain said was aimed at blowing up at least one of the planes.

The arrest came after two packages containing explosives and addressed to Jewish synagogues in Chicago were intercepted on cargo aircraft in Dubai and Britain,unleashing fears of a renewed Al-Qaeda terror offensive against the US and European nations.

US President Barack Obama suspecting the involvement of Al-Qaeda in the Arabian Peninsula AQAP,the Yemen-based branch of Osama bin Laden8217;s extremist network,warned that US will not spare any effort to investigate the origins of Chicago-bound packages.

Evidence was mounting that the top leadership of Al-Qaeda in the Arabian Peninsula,including the radical American-born cleric Anwar al-Awlaki,was behind the attempted attacks,8217;The Times8217; quoted US officials as saying.

Investigating officials said that the bomb discovered at the Dubai airport was concealed in a Hewlett-Packard desktop printer,with high explosives packed into a printer cartridge to avoid detection by scanners,the paper said.

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8220;The wiring of the device indicates that this was done by professionals,8221; the paper quoted an official involved in the investigation as saying. 8220;It was set up so that if you scan it,all the printer components would look right.8221;

The Washington Post said investigators were focusing on a Saudi bomb-maker who last year sent his brother to death in an effort to kill a Saudi prince.

Ibrahim Hassan al-Asiri,a 28-year-old man who is on Saudi Arabia8217;s most-wanted list,introduced a PETN-based bomb in a body cavity of his younger brother,Abdullah,who pretended to be turning himself in,The Post said.

The bomb killed his brother and wounded Mohammed bin Nayef,a top counterterrorism official and Saudi royal.

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Yemen based Asiri,is also believed to have built the underwear bomb of Farouk Abdulmutallab,a Nigerian man who was trained in Yemen and attempted to blow up a commercial aircraft approaching Detroit last December,the Post report said.

That device also contained PETN,or pentaerythritol trinitrate.

8220;He is certainly someone we are focused on,8221; the paper quotes an unnamed US official as saying of Asiri.