Chief executive hopefuls Henry Tang Ying-yen and Leung Chun-ying traded blows yesterday over the best way to manage the influx of mainland women coming to the city to give birth. A day after business and entertainment heavyweights turned out in force at a campaign rally for Tang, the former chief secretary countered Leung's suggestion that the authorities stem the tide of pregnant mainland women by having immigration officers block the women at border checkpoints. Tang did not respond directly to the idea but said a better way to deal with the issue could be to prevent all pregnant mainland women not married to locals from giving birth in public hospitals and channelling them to private medical facilities. The government has capped the number of maternity beds for non-local mothers in public and private hospitals at 34,400 next year. Tang said the government could consider scrapping the quota for public hospitals and continuing to offer a limited number of places in private centres. At the centre of the maternity issue is the right of abode granted to all children born in the city - a big incentive for mainland women to come to Hong Kong to give birth. In response to a radio talkback show caller who asked if the government could design a system to deny the right of abode to the Hong Kong-born children of mainland mothers, Tang said that this could be done only by amending the Basic Law or seeking an interpretation from the National People's Congress Standing Committee. 'Each choice presents difficulties to overcome. I believe if we sought an interpretation of the Basic Law, it would deal a blow to the rule of law of Hong Kong,' he said after the show, before heading to Lok Fu and Central to hand out leaflets promoting his platform. 'On the other hand, it would also be difficult to amend the Basic Law. So I think at this stage, we should use the quota system instead.' Leung said that stopping public hospitals from providing services to pregnant mainland women would not fix the problem. The women might then flood private hospitals, affecting services to city residents, especially the middle class. Leung said the city should not rely on a Basic Law interpretation from Beijing because it was a complex process and would not address the short-term pressure on the obstetrics system. 'It's not an easy decision to seek Beijing's interpretation of the Basic Law,' the former Executive Council convenor said. 'Seeking an interpretation can only address issues concerning the children's identities, which is a more long-term problem.' Given that the obstetrics services for local mothers were already being affected, using administrative means to stop mainland mothers-to-be at border checkpoints was the best way because it was quicker and would not involve the Basic Law. Tang sidestepped questions on the nomination threshold for the first 'one-man one-vote' chief executive election, due in 2017. 'We should collect more ideas by listening to the public's views,' he said. 'No matter how big or small the step, we must take the first step. After making this step, we will enhance and not worsen [the system] in the future.'