Yemen has resolved a months-long spat with Ukraine that had threatened to derail its bid to join the World Trade Organization, the WTO said on Thursday.

The agreement puts Yemen back on course to join the world trade body as early as the end of 2012. That would make it the 159th member after Russia and Vanuatu, which will both become members in August, and Laos, which is finalizing entry terms.

Every new WTO member has to bring its own laws into line with WTO standards and agree to open trade to satisfy every existing member. That gives every member an effective veto on new joiners.

WTO spokesman Keith Rockwell said Ukraine had agreed terms with Yemen, enabling the WTO’s working party on Yemen’s accession to hold a final meeting in late September. The wider WTO membership will then approve Yemen’s membership package and send it back to Yemen for ratification.

Ukraine’s tough demands on Yemen had caused friction at the WTO, where some diplomats saw its stance as going against the grain of a new push to make it easier for poorer countries such as Yemen to join.

Three senior WTO diplomats were helping to facilitate the negotiations between Yemen and Ukraine, but Ukraine warned them earlier this month not to interfere in its sovereign right to negotiate with Yemen and to demand lower trade barriers.

Ukraine’s insistence on wringing concessions out of Yemen had mystified many WTO diplomats, since it does very little trade with the Arab country. It had also earlier held out against Laos’ membership, but the two sides reached a deal at the start of June.