Opposition parties stepped up criticism Monday of an envisaged shake-up of Japan's immigration control law as its passage through the Lower House grew near, slamming Prime Minister Shinzo Abe's interpretation of immigrants that they said was out of line with "global standards."

The bulk of Monday's Diet deliberations were spent scrutinizing a bill set to overhaul the immigration control law, in changes intended to assuage the country's severe labor crunch that stems from its graying population. Opposition parties are fiercely opposed to its passage through the Lower House, currently slated for Tuesday.

Abe may even cut short a diplomatic tour planned for early next month in an apparent bid to focus more on Diet debate over the bill. Media reports said Monday he is considering canceling his trip to Britain and the Netherlands after attending a summit of the Group of 20 advanced and emerging economies in Argentina, which starts Friday. He is now likely to return to Japan on Dec. 4, instead of originally scheduled Dec. 7, Kyodo News quoted government sources as saying.